[PATCH v4 0/2] CPUFreq driver using CPPC methods

[PATCH v4 0/2] CPUFreq driver using CPPC methods

[Ashwin Chaugule]

CPPC:
====

CPPC (Collaborative Processor Performance Control) is a new way to control CPU
performance using an abstract continous scale as against a discretized P-state scale
which is tied to CPU frequency only. It is defined in the ACPI 5.0+ spec. In brief,
the basic operation involves:
- OS makes a CPU performance request. (Can provide min and max tolerable bounds)

- Platform (such as BMC) is free to optimize request within requested bounds depending
on power/thermal budgets etc.

- Platform conveys its decision back to OS

The communication between OS and platform occurs through another medium called (PCC)
Platform communication Channel. This is a generic mailbox like mechanism which includes
doorbell semantics to indicate register updates. See drivers/mailbox/pcc.c

This patchset introduces a CPPC based CPUFreq driver that works with existing governors
such as ondemand. The CPPC table parsing and the CPPC communication semantics are
abstracted into separate files to allow future CPPC based drivers to implement their
own governors if required.

Initial patchsets included an adaptation of the PID governor from intel_pstate.c. However
recent experiments led to extensive modifications of the algorithm to calculate CPU
busyness. Until it is verified that these changes are worthwhile, the existing governors
should provide for a good enough starting point for ARM64 servers.

Finer details about the PCC and CPPC spec are available in the latest ACPI 5.1
specification.[2]

Changes since V3:
- Split CPPC backend methods into separate files.
- Add frontend driver which plugs into existing CPUfreq governors.
- Simplify PCC driver by moving communication space mapping and read/write
	into client drivers.

Changes since V2:
- Select driver if !X86, since intel_pstate will use HWP extensions instead.
- Added more comments.
- Added Freq domain awareness and PSD parsing.

Changes since V1:
- Create a new driver based on Dirks suggestion.
- Fold in CPPC backend hooks into main driver.

Changes since V0: [1]
- Split intel_pstate.c into a generic PID governor and platform specific backend.
- Add CPPC accessors as PID backend.

[1] - http://lwn.net/Articles/608715/
[2] - http://www.uefi.org/sites/default/files/resources/ACPI_5_1release.pdf
[3] - https://patches.linaro.org/40705/


Ashwin Chaugule (2):
  Mailbox: Restructure and simplify PCC mailbox code
  CPPC: Add CPUFreq driver based on CPPC methods

 drivers/cpufreq/Kconfig.arm    |  15 +
 drivers/cpufreq/Makefile       |   1 +
 drivers/cpufreq/cppc_acpi.c    | 801 +++++++++++++++++++++++++++++++++++++++++
 drivers/cpufreq/cppc_acpi.h    | 134 +++++++
 drivers/cpufreq/cppc_cpufreq.c | 186 ++++++++++
 drivers/mailbox/pcc.c          | 122 ++-----
 6 files changed, 1174 insertions(+), 85 deletions(-)
 create mode 100644 drivers/cpufreq/cppc_acpi.c
 create mode 100644 drivers/cpufreq/cppc_acpi.h
 create mode 100644 drivers/cpufreq/cppc_cpufreq.c

-- 
1.9.1

[PATCH v4 1/2] Mailbox: Restructure and simplify PCC mailbox code

[Ashwin Chaugule]

Previously the PCC driver depended on the client
side to map the communication space base address. This region
was was then used in the PCC driver and the client side.
The client side used this region to read and write its data
and the PCC driver used it to only write the PCC command.
Removing this split simplifies the PCC driver a lot. This patch
moves all communication region read/writes to the client side.
The PCC clients can now drive the PCC mailbox controller via the
mbox_client_txdone() method.

Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
---
 drivers/mailbox/pcc.c | 122 +++++++++++++++-----------------------------------
 1 file changed, 37 insertions(+), 85 deletions(-)

diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
index 6dbf6fc..e0c8e29 100644
--- a/drivers/mailbox/pcc.c
+++ b/drivers/mailbox/pcc.c
@@ -20,10 +20,35 @@
  *  shared memory regions as defined in the PCC table entries. The PCC
  *  specification supports a Doorbell mechanism for the PCC clients
  *  to notify the platform about new data. This Doorbell information
- *  is also specified in each PCC table entry. See pcc_send_data()
- *  and pcc_tx_done() for basic mode of operation.
+ *  is also specified in each PCC table entry.
  *
- *  For more details about PCC, please see the ACPI specification from
+ *  Typical high level flow of operation is:
+ *
+ *  PCC Reads:
+ *  * Client tries to acquire a channel lock.
+ *  * After it is acquired it writes READ cmd in communication region cmd
+ *		address.
+ *  * Client issues mbox_send_message() which rings the PCC doorbell
+ *		for its PCC channel.
+ *  * If command completes, then client has control over channel and
+ *		it can proceed with its reads.
+ *  * Client releases lock.
+ *
+ *  PCC Writes:
+ *  * Client tries to acquire channel lock.
+ *  * Client writes to its communication region after it acquires a
+ *		channel lock.
+ *  * Client writes WRITE cmd in communication region cmd address.
+ *  * Client issues mbox_send_message() which rings the PCC doorbell
+ *		for its PCC channel.
+ *  * If command completes, then writes have succeded and it can release
+ *		the channel lock.
+ *
+ *  There is a Nominal latency defined for each channel which indicates
+ *  how long to wait until a command completes. If command is not complete
+ *  the client needs to retry or assume failure.
+ *
+ *	For more details about PCC, please see the ACPI specification from
  *  http://www.uefi.org/ACPIv5.1 Section 14.
  *
  *  This file implements PCC as a Mailbox controller and allows for PCC
@@ -42,8 +67,6 @@
 #include "mailbox.h"
 
 #define MAX_PCC_SUBSPACES	256
-#define PCCS_SS_SIG_MAGIC	0x50434300
-#define PCC_CMD_COMPLETE	0x1
 
 static struct mbox_chan *pcc_mbox_channels;
 
@@ -71,23 +94,6 @@ static struct mbox_chan *get_pcc_channel(int id)
 }
 
 /**
- * get_subspace_id - Given a Mailbox channel, find out the
- *		PCC subspace id.
- * @chan: Pointer to Mailbox Channel from which we want
- *		the index.
- * Return: Errno if not found, else positive index number.
- */
-static int get_subspace_id(struct mbox_chan *chan)
-{
-	unsigned int id = chan - pcc_mbox_channels;
-
-	if (id < 0 || id > pcc_mbox_ctrl.num_chans)
-		return -ENOENT;
-
-	return id;
-}
-
-/**
  * pcc_mbox_request_channel - PCC clients call this function to
  *		request a pointer to their PCC subspace, from which they
  *		can get the details of communicating with the remote.
@@ -117,7 +123,7 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
 	chan = get_pcc_channel(subspace_id);
 
 	if (!chan || chan->cl) {
-		dev_err(dev, "%s: PCC mailbox not free\n", __func__);
+		dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
 		return ERR_PTR(-EBUSY);
 	}
 
@@ -161,81 +167,30 @@ void pcc_mbox_free_channel(struct mbox_chan *chan)
 EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
 
 /**
- * pcc_tx_done - Callback from Mailbox controller code to
- *		check if PCC message transmission completed.
- * @chan: Pointer to Mailbox channel on which previous
- *		transmission occurred.
- *
- * Return: TRUE if succeeded.
- */
-static bool pcc_tx_done(struct mbox_chan *chan)
-{
-	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
-	struct acpi_pcct_shared_memory *generic_comm_base =
-		(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
-	u16 cmd_delay = pcct_ss->latency;
-	unsigned int retries = 0;
-
-	/* Try a few times while waiting for platform to consume */
-	while (!(readw_relaxed(&generic_comm_base->status)
-		    & PCC_CMD_COMPLETE)) {
-
-		if (retries++ < 5)
-			udelay(cmd_delay);
-		else {
-			/*
-			 * If the remote is dead, this will cause the Mbox
-			 * controller to timeout after mbox client.tx_tout
-			 * msecs.
-			 */
-			pr_err("PCC platform did not respond.\n");
-			return false;
-		}
-	}
-	return true;
-}
-
-/**
- * pcc_send_data - Called from Mailbox Controller code to finally
- *	transmit data over channel.
+ * pcc_send_data - Called from Mailbox Controller code. Used
+ *		here only to ring the channel doorbell. The PCC client
+ *		specific read/write is done in the client driver in
+ *		order to maintain atomicity over PCC channel once
+ *		OS has control over it. See above for flow of operations.
  * @chan: Pointer to Mailbox channel over which to send data.
- * @data: Actual data to be written over channel.
+ * @data: Client specific data written over channel. Used here
+ *		only for debug after PCC transaction completes.
  *
  * Return: Err if something failed else 0 for success.
  */
 static int pcc_send_data(struct mbox_chan *chan, void *data)
 {
 	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
-	struct acpi_pcct_shared_memory *generic_comm_base =
-		(struct acpi_pcct_shared_memory *) pcct_ss->base_address;
 	struct acpi_generic_address doorbell;
 	u64 doorbell_preserve;
 	u64 doorbell_val;
 	u64 doorbell_write;
-	u16 cmd = *(u16 *) data;
-	u16 ss_idx = -1;
-
-	ss_idx = get_subspace_id(chan);
-
-	if (ss_idx < 0) {
-		pr_err("Invalid Subspace ID from PCC client\n");
-		return -EINVAL;
-	}
 
 	doorbell = pcct_ss->doorbell_register;
 	doorbell_preserve = pcct_ss->preserve_mask;
 	doorbell_write = pcct_ss->write_mask;
 
-	/* Write to the shared comm region. */
-	writew(cmd, &generic_comm_base->command);
-
-	/* Write Subspace MAGIC value so platform can identify destination. */
-	writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
-
-	/* Flip CMD COMPLETE bit */
-	writew(0, &generic_comm_base->status);
-
-	/* Sync notification from OSPM to Platform. */
+	/* Sync notification from OS to Platform. */
 	acpi_read(&doorbell_val, &doorbell);
 	acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
 			&doorbell);
@@ -245,7 +200,6 @@ static int pcc_send_data(struct mbox_chan *chan, void *data)
 
 static struct mbox_chan_ops pcc_chan_ops = {
 	.send_data = pcc_send_data,
-	.last_tx_done = pcc_tx_done,
 };
 
 /**
@@ -351,8 +305,6 @@ static int pcc_mbox_probe(struct platform_device *pdev)
 
 	pcc_mbox_ctrl.chans = pcc_mbox_channels;
 	pcc_mbox_ctrl.ops = &pcc_chan_ops;
-	pcc_mbox_ctrl.txdone_poll = true;
-	pcc_mbox_ctrl.txpoll_period = 10;
 	pcc_mbox_ctrl.dev = &pdev->dev;
 
 	pr_info("Registering PCC driver as Mailbox controller\n");
-- 
1.9.1

Re: [PATCH v4 1/2] Mailbox: Restructure and simplify PCC mailbox code

[Ashwin Chaugule]

Hello,

On 27 January 2015 at 16:03, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote:
> Previously the PCC driver depended on the client
> side to map the communication space base address. This region
> was was then used in the PCC driver and the client side.
> The client side used this region to read and write its data
> and the PCC driver used it to only write the PCC command.
> Removing this split simplifies the PCC driver a lot. This patch
> moves all communication region read/writes to the client side.
> The PCC clients can now drive the PCC mailbox controller via the
> mbox_client_txdone() method.
>
> Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> ---
>  drivers/mailbox/pcc.c | 122 +++++++++++++++-----------------------------------
>  1 file changed, 37 insertions(+), 85 deletions(-)

Gentle reminder for this patch specifically. It can be pulled in by
itself separately from the CPPC patch[2/2], which understandably may
need more time for review. Apart from the simplification done here,
there is one more change based on a comment I got from Rafael to
convert a pr_err() in the init function to pr_debug(). The "PCC Probe
failed" message seems to be raising false positives on X86 test
reports. Please let me know if there are any other suggestions, before
I respin another version for this.

Thanks,
Ashwin.

>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 6dbf6fc..e0c8e29 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -20,10 +20,35 @@
>   *  shared memory regions as defined in the PCC table entries. The PCC
>   *  specification supports a Doorbell mechanism for the PCC clients
>   *  to notify the platform about new data. This Doorbell information
> - *  is also specified in each PCC table entry. See pcc_send_data()
> - *  and pcc_tx_done() for basic mode of operation.
> + *  is also specified in each PCC table entry.
>   *
> - *  For more details about PCC, please see the ACPI specification from
> + *  Typical high level flow of operation is:
> + *
> + *  PCC Reads:
> + *  * Client tries to acquire a channel lock.
> + *  * After it is acquired it writes READ cmd in communication region cmd
> + *             address.
> + *  * Client issues mbox_send_message() which rings the PCC doorbell
> + *             for its PCC channel.
> + *  * If command completes, then client has control over channel and
> + *             it can proceed with its reads.
> + *  * Client releases lock.
> + *
> + *  PCC Writes:
> + *  * Client tries to acquire channel lock.
> + *  * Client writes to its communication region after it acquires a
> + *             channel lock.
> + *  * Client writes WRITE cmd in communication region cmd address.
> + *  * Client issues mbox_send_message() which rings the PCC doorbell
> + *             for its PCC channel.
> + *  * If command completes, then writes have succeded and it can release
> + *             the channel lock.
> + *
> + *  There is a Nominal latency defined for each channel which indicates
> + *  how long to wait until a command completes. If command is not complete
> + *  the client needs to retry or assume failure.
> + *
> + *     For more details about PCC, please see the ACPI specification from
>   *  http://www.uefi.org/ACPIv5.1 Section 14.
>   *
>   *  This file implements PCC as a Mailbox controller and allows for PCC
> @@ -42,8 +67,6 @@
>  #include "mailbox.h"
>
>  #define MAX_PCC_SUBSPACES      256
> -#define PCCS_SS_SIG_MAGIC      0x50434300
> -#define PCC_CMD_COMPLETE       0x1
>
>  static struct mbox_chan *pcc_mbox_channels;
>
> @@ -71,23 +94,6 @@ static struct mbox_chan *get_pcc_channel(int id)
>  }
>
>  /**
> - * get_subspace_id - Given a Mailbox channel, find out the
> - *             PCC subspace id.
> - * @chan: Pointer to Mailbox Channel from which we want
> - *             the index.
> - * Return: Errno if not found, else positive index number.
> - */
> -static int get_subspace_id(struct mbox_chan *chan)
> -{
> -       unsigned int id = chan - pcc_mbox_channels;
> -
> -       if (id < 0 || id > pcc_mbox_ctrl.num_chans)
> -               return -ENOENT;
> -
> -       return id;
> -}
> -
> -/**
>   * pcc_mbox_request_channel - PCC clients call this function to
>   *             request a pointer to their PCC subspace, from which they
>   *             can get the details of communicating with the remote.
> @@ -117,7 +123,7 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
>         chan = get_pcc_channel(subspace_id);
>
>         if (!chan || chan->cl) {
> -               dev_err(dev, "%s: PCC mailbox not free\n", __func__);
> +               dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
>                 return ERR_PTR(-EBUSY);
>         }
>
> @@ -161,81 +167,30 @@ void pcc_mbox_free_channel(struct mbox_chan *chan)
>  EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
>
>  /**
> - * pcc_tx_done - Callback from Mailbox controller code to
> - *             check if PCC message transmission completed.
> - * @chan: Pointer to Mailbox channel on which previous
> - *             transmission occurred.
> - *
> - * Return: TRUE if succeeded.
> - */
> -static bool pcc_tx_done(struct mbox_chan *chan)
> -{
> -       struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
> -       struct acpi_pcct_shared_memory *generic_comm_base =
> -               (struct acpi_pcct_shared_memory *) pcct_ss->base_address;
> -       u16 cmd_delay = pcct_ss->latency;
> -       unsigned int retries = 0;
> -
> -       /* Try a few times while waiting for platform to consume */
> -       while (!(readw_relaxed(&generic_comm_base->status)
> -                   & PCC_CMD_COMPLETE)) {
> -
> -               if (retries++ < 5)
> -                       udelay(cmd_delay);
> -               else {
> -                       /*
> -                        * If the remote is dead, this will cause the Mbox
> -                        * controller to timeout after mbox client.tx_tout
> -                        * msecs.
> -                        */
> -                       pr_err("PCC platform did not respond.\n");
> -                       return false;
> -               }
> -       }
> -       return true;
> -}
> -
> -/**
> - * pcc_send_data - Called from Mailbox Controller code to finally
> - *     transmit data over channel.
> + * pcc_send_data - Called from Mailbox Controller code. Used
> + *             here only to ring the channel doorbell. The PCC client
> + *             specific read/write is done in the client driver in
> + *             order to maintain atomicity over PCC channel once
> + *             OS has control over it. See above for flow of operations.
>   * @chan: Pointer to Mailbox channel over which to send data.
> - * @data: Actual data to be written over channel.
> + * @data: Client specific data written over channel. Used here
> + *             only for debug after PCC transaction completes.
>   *
>   * Return: Err if something failed else 0 for success.
>   */
>  static int pcc_send_data(struct mbox_chan *chan, void *data)
>  {
>         struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
> -       struct acpi_pcct_shared_memory *generic_comm_base =
> -               (struct acpi_pcct_shared_memory *) pcct_ss->base_address;
>         struct acpi_generic_address doorbell;
>         u64 doorbell_preserve;
>         u64 doorbell_val;
>         u64 doorbell_write;
> -       u16 cmd = *(u16 *) data;
> -       u16 ss_idx = -1;
> -
> -       ss_idx = get_subspace_id(chan);
> -
> -       if (ss_idx < 0) {
> -               pr_err("Invalid Subspace ID from PCC client\n");
> -               return -EINVAL;
> -       }
>
>         doorbell = pcct_ss->doorbell_register;
>         doorbell_preserve = pcct_ss->preserve_mask;
>         doorbell_write = pcct_ss->write_mask;
>
> -       /* Write to the shared comm region. */
> -       writew(cmd, &generic_comm_base->command);
> -
> -       /* Write Subspace MAGIC value so platform can identify destination. */
> -       writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
> -
> -       /* Flip CMD COMPLETE bit */
> -       writew(0, &generic_comm_base->status);
> -
> -       /* Sync notification from OSPM to Platform. */
> +       /* Sync notification from OS to Platform. */
>         acpi_read(&doorbell_val, &doorbell);
>         acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
>                         &doorbell);
> @@ -245,7 +200,6 @@ static int pcc_send_data(struct mbox_chan *chan, void *data)
>
>  static struct mbox_chan_ops pcc_chan_ops = {
>         .send_data = pcc_send_data,
> -       .last_tx_done = pcc_tx_done,
>  };
>
>  /**
> @@ -351,8 +305,6 @@ static int pcc_mbox_probe(struct platform_device *pdev)
>
>         pcc_mbox_ctrl.chans = pcc_mbox_channels;
>         pcc_mbox_ctrl.ops = &pcc_chan_ops;
> -       pcc_mbox_ctrl.txdone_poll = true;
> -       pcc_mbox_ctrl.txpoll_period = 10;
>         pcc_mbox_ctrl.dev = &pdev->dev;
>
>         pr_info("Registering PCC driver as Mailbox controller\n");
> --
> 1.9.1
>

Re: [PATCH v4 1/2] Mailbox: Restructure and simplify PCC mailbox code

[Rafael J. Wysocki]

On Friday, February 13, 2015 08:07:44 AM Ashwin Chaugule wrote:
> Hello,
> 
> On 27 January 2015 at 16:03, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote:
> > Previously the PCC driver depended on the client
> > side to map the communication space base address. This region
> > was was then used in the PCC driver and the client side.
> > The client side used this region to read and write its data
> > and the PCC driver used it to only write the PCC command.
> > Removing this split simplifies the PCC driver a lot. This patch
> > moves all communication region read/writes to the client side.
> > The PCC clients can now drive the PCC mailbox controller via the
> > mbox_client_txdone() method.
> >
> > Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> > ---
> >  drivers/mailbox/pcc.c | 122 +++++++++++++++-----------------------------------
> >  1 file changed, 37 insertions(+), 85 deletions(-)
> 
> Gentle reminder for this patch specifically. It can be pulled in by
> itself separately from the CPPC patch[2/2], which understandably may
> need more time for review. Apart from the simplification done here,
> there is one more change based on a comment I got from Rafael to
> convert a pr_err() in the init function to pr_debug(). The "PCC Probe
> failed" message seems to be raising false positives on X86 test
> reports. Please let me know if there are any other suggestions, before
> I respin another version for this.

The patch changing the pr_err() to pr_debug() is in the Linus' tree already
as far as I can say.

Besides, this should be To: the maintainer of the mailbox susbsystem (not
me) or if you want me to pick it up, I need and ACK from that maintainer
anyway.


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH v4 1/2] Mailbox: Restructure and simplify PCC mailbox code

[Ashwin Chaugule]

Hi Rafael,

On 13 February 2015 at 09:38, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Friday, February 13, 2015 08:07:44 AM Ashwin Chaugule wrote:
>> Hello,
>>
>> On 27 January 2015 at 16:03, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote:
>> > Previously the PCC driver depended on the client
>> > side to map the communication space base address. This region
>> > was was then used in the PCC driver and the client side.
>> > The client side used this region to read and write its data
>> > and the PCC driver used it to only write the PCC command.
>> > Removing this split simplifies the PCC driver a lot. This patch
>> > moves all communication region read/writes to the client side.
>> > The PCC clients can now drive the PCC mailbox controller via the
>> > mbox_client_txdone() method.
>> >
>> > Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
>> > ---
>> >  drivers/mailbox/pcc.c | 122 +++++++++++++++-----------------------------------
>> >  1 file changed, 37 insertions(+), 85 deletions(-)
>>
>> Gentle reminder for this patch specifically. It can be pulled in by
>> itself separately from the CPPC patch[2/2], which understandably may
>> need more time for review. Apart from the simplification done here,
>> there is one more change based on a comment I got from Rafael tow
>> convert a pr_err() in the init function to pr_debug(). The "PCC Probe
>> failed" message seems to be raising false positives on X86 test
>> reports. Please let me know if there are any other suggestions, before
>> I respin another version for this.
>
> The patch changing the pr_err() to pr_debug() is in the Linus' tree already
> as far as I can say.

Thanks for that.

>
> Besides, this should be To: the maintainer of the mailbox susbsystem (not
> me) or if you want me to pick it up, I need and ACK from that maintainer
> anyway.

Is there a way to do that separately for each patch in a patchset?
Anyway, I'll rebase this patch to tip and send it separately To:
Jassi.

Thanks,
Ashwin.

Re: [PATCH v4 1/2] Mailbox: Restructure and simplify PCC mailbox code

[Ashwin Chaugule]

On 13 February 2015 at 18:31, Ashwin Chaugule
<ashwin.chaugule@linaro.org> wrote:
> Hi Rafael,
>
> On 13 February 2015 at 09:38, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>> On Friday, February 13, 2015 08:07:44 AM Ashwin Chaugule wrote:
>>> Hello,
>>>
>>> On 27 January 2015 at 16:03, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote:
>>> > Previously the PCC driver depended on the client
>>> > side to map the communication space base address. This region
>>> > was was then used in the PCC driver and the client side.
>>> > The client side used this region to read and write its data
>>> > and the PCC driver used it to only write the PCC command.
>>> > Removing this split simplifies the PCC driver a lot. This patch
>>> > moves all communication region read/writes to the client side.
>>> > The PCC clients can now drive the PCC mailbox controller via the
>>> > mbox_client_txdone() method.
>>> >
>>> > Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
>>> > ---
>>> >  drivers/mailbox/pcc.c | 122 +++++++++++++++-----------------------------------
>>> >  1 file changed, 37 insertions(+), 85 deletions(-)
>>>
>>> Gentle reminder for this patch specifically. It can be pulled in by
>>> itself separately from the CPPC patch[2/2], which understandably may
>>> need more time for review. Apart from the simplification done here,
>>> there is one more change based on a comment I got from Rafael tow
>>> convert a pr_err() in the init function to pr_debug(). The "PCC Probe
>>> failed" message seems to be raising false positives on X86 test
>>> reports. Please let me know if there are any other suggestions, before
>>> I respin another version for this.
>>
>> The patch changing the pr_err() to pr_debug() is in the Linus' tree already
>> as far as I can say.
>
> Thanks for that.
>
>>
>> Besides, this should be To: the maintainer of the mailbox susbsystem (not
>> me) or if you want me to pick it up, I need and ACK from that maintainer
>> anyway.
>
> Is there a way to do that separately for each patch in a patchset?
> Anyway, I'll rebase this patch to tip and send it separately To:
> Jassi.

Rebasing to tip and applying this patch didnt cause any merge
conflicts. So I think instead of generating more patch traffic just
yet, its probably better to review this as is. Let me know if anyone
thinks otherwise. I'll try to ping Jassi offline.

Thanks,
Ashwin.

Re: [PATCH v4 1/2] Mailbox: Restructure and simplify PCC mailbox code

[Rafael J. Wysocki]

On Friday, February 13, 2015 07:01:30 PM Ashwin Chaugule wrote:
> On 13 February 2015 at 18:31, Ashwin Chaugule
> <ashwin.chaugule@linaro.org> wrote:
> > Hi Rafael,
> >
> > On 13 February 2015 at 09:38, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> >> On Friday, February 13, 2015 08:07:44 AM Ashwin Chaugule wrote:
> >>> Hello,
> >>>
> >>> On 27 January 2015 at 16:03, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote:
> >>> > Previously the PCC driver depended on the client
> >>> > side to map the communication space base address. This region
> >>> > was was then used in the PCC driver and the client side.
> >>> > The client side used this region to read and write its data
> >>> > and the PCC driver used it to only write the PCC command.
> >>> > Removing this split simplifies the PCC driver a lot. This patch
> >>> > moves all communication region read/writes to the client side.
> >>> > The PCC clients can now drive the PCC mailbox controller via the
> >>> > mbox_client_txdone() method.
> >>> >
> >>> > Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> >>> > ---
> >>> >  drivers/mailbox/pcc.c | 122 +++++++++++++++-----------------------------------
> >>> >  1 file changed, 37 insertions(+), 85 deletions(-)
> >>>
> >>> Gentle reminder for this patch specifically. It can be pulled in by
> >>> itself separately from the CPPC patch[2/2], which understandably may
> >>> need more time for review. Apart from the simplification done here,
> >>> there is one more change based on a comment I got from Rafael tow
> >>> convert a pr_err() in the init function to pr_debug(). The "PCC Probe
> >>> failed" message seems to be raising false positives on X86 test
> >>> reports. Please let me know if there are any other suggestions, before
> >>> I respin another version for this.
> >>
> >> The patch changing the pr_err() to pr_debug() is in the Linus' tree already
> >> as far as I can say.
> >
> > Thanks for that.
> >
> >>
> >> Besides, this should be To: the maintainer of the mailbox susbsystem (not
> >> me) or if you want me to pick it up, I need and ACK from that maintainer
> >> anyway.
> >
> > Is there a way to do that separately for each patch in a patchset?
> > Anyway, I'll rebase this patch to tip and send it separately To:
> > Jassi.
> 
> Rebasing to tip and applying this patch didnt cause any merge
> conflicts. So I think instead of generating more patch traffic just
> yet, its probably better to review this as is. Let me know if anyone
> thinks otherwise. I'll try to ping Jassi offline.

Can you please remind me what the status here is?  Is this the final version
I'm supposed to review or are you going to submit a new one?


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH v4 1/2] Mailbox: Restructure and simplify PCC mailbox code

[Ashwin Chaugule]

Hi Rafael,

On 12 March 2015 at 19:28, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Friday, February 13, 2015 07:01:30 PM Ashwin Chaugule wrote:
>> On 13 February 2015 at 18:31, Ashwin Chaugule
>> <ashwin.chaugule@linaro.org> wrote:
>> > Hi Rafael,
>> >
>> > On 13 February 2015 at 09:38, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>> >> On Friday, February 13, 2015 08:07:44 AM Ashwin Chaugule wrote:
>> >>> Hello,
>> >>>
>> >>> On 27 January 2015 at 16:03, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote:
>> >>> > Previously the PCC driver depended on the client
>> >>> > side to map the communication space base address. This region
>> >>> > was was then used in the PCC driver and the client side.
>> >>> > The client side used this region to read and write its data
>> >>> > and the PCC driver used it to only write the PCC command.
>> >>> > Removing this split simplifies the PCC driver a lot. This patch
>> >>> > moves all communication region read/writes to the client side.
>> >>> > The PCC clients can now drive the PCC mailbox controller via the
>> >>> > mbox_client_txdone() method.
>> >>> >
>> >>> > Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
>> >>> > ---
>> >>> >  drivers/mailbox/pcc.c | 122 +++++++++++++++-----------------------------------
>> >>> >  1 file changed, 37 insertions(+), 85 deletions(-)
>> >>>
>> >>> Gentle reminder for this patch specifically. It can be pulled in by
>> >>> itself separately from the CPPC patch[2/2], which understandably may
>> >>> need more time for review. Apart from the simplification done here,
>> >>> there is one more change based on a comment I got from Rafael tow
>> >>> convert a pr_err() in the init function to pr_debug(). The "PCC Probe
>> >>> failed" message seems to be raising false positives on X86 test
>> >>> reports. Please let me know if there are any other suggestions, before
>> >>> I respin another version for this.
>> >>
>> >> The patch changing the pr_err() to pr_debug() is in the Linus' tree already
>> >> as far as I can say.
>> >
>> > Thanks for that.
>> >
>> >>
>> >> Besides, this should be To: the maintainer of the mailbox susbsystem (not
>> >> me) or if you want me to pick it up, I need and ACK from that maintainer
>> >> anyway.
>> >
>> > Is there a way to do that separately for each patch in a patchset?
>> > Anyway, I'll rebase this patch to tip and send it separately To:
>> > Jassi.
>>
>> Rebasing to tip and applying this patch didnt cause any merge
>> conflicts. So I think instead of generating more patch traffic just
>> yet, its probably better to review this as is. Let me know if anyone
>> thinks otherwise. I'll try to ping Jassi offline.
>
> Can you please remind me what the status here is?  Is this the final version
> I'm supposed to review or are you going to submit a new one?

This is the final one. The only change to this would be to make PCC
depend on CPPC. But that can be added along with the CPPC patch when
it is ready for upstreaming.

Thanks,
Ashwin.

Re: [PATCH v4 1/2] Mailbox: Restructure and simplify PCC mailbox code

[Ashwin Chaugule]

On 12 March 2015 at 19:28, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Friday, February 13, 2015 07:01:30 PM Ashwin Chaugule wrote:
>> On 13 February 2015 at 18:31, Ashwin Chaugule
>> <ashwin.chaugule@linaro.org> wrote:
>> > Hi Rafael,
>> >
>> > On 13 February 2015 at 09:38, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>> >> On Friday, February 13, 2015 08:07:44 AM Ashwin Chaugule wrote:
>> >>> Hello,
>> >>>
>> >>> On 27 January 2015 at 16:03, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote:
>> >>> > Previously the PCC driver depended on the client
>> >>> > side to map the communication space base address. This region
>> >>> > was was then used in the PCC driver and the client side.
>> >>> > The client side used this region to read and write its data
>> >>> > and the PCC driver used it to only write the PCC command.
>> >>> > Removing this split simplifies the PCC driver a lot. This patch
>> >>> > moves all communication region read/writes to the client side.
>> >>> > The PCC clients can now drive the PCC mailbox controller via the
>> >>> > mbox_client_txdone() method.
>> >>> >
>> >>> > Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
>> >>> > ---
>> >>> >  drivers/mailbox/pcc.c | 122 +++++++++++++++-----------------------------------
>> >>> >  1 file changed, 37 insertions(+), 85 deletions(-)
>> >>>
>> >>> Gentle reminder for this patch specifically. It can be pulled in by
>> >>> itself separately from the CPPC patch[2/2], which understandably may
>> >>> need more time for review. Apart from the simplification done here,
>> >>> there is one more change based on a comment I got from Rafael tow
>> >>> convert a pr_err() in the init function to pr_debug(). The "PCC Probe
>> >>> failed" message seems to be raising false positives on X86 test
>> >>> reports. Please let me know if there are any other suggestions, before
>> >>> I respin another version for this.
>> >>
>> >> The patch changing the pr_err() to pr_debug() is in the Linus' tree already
>> >> as far as I can say.
>> >
>> > Thanks for that.
>> >
>> >>
>> >> Besides, this should be To: the maintainer of the mailbox susbsystem (not
>> >> me) or if you want me to pick it up, I need and ACK from that maintainer
>> >> anyway.
>> >
>> > Is there a way to do that separately for each patch in a patchset?
>> > Anyway, I'll rebase this patch to tip and send it separately To:
>> > Jassi.
>>
>> Rebasing to tip and applying this patch didnt cause any merge
>> conflicts. So I think instead of generating more patch traffic just
>> yet, its probably better to review this as is. Let me know if anyone
>> thinks otherwise. I'll try to ping Jassi offline.
>
> Can you please remind me what the status here is?  Is this the final version
> I'm supposed to review or are you going to submit a new one?

As a heads up, Jassi had already picked up this patch in his tree:

https://git.linaro.org/landing-teams/working/fujitsu/integration.git/shortlog/refs/heads/mailbox-devel

Thanks,
Ashwin.

[PATCH v4 2/2] CPPC: Add CPUFreq driver based on CPPC methods

[Ashwin Chaugule]

CPPC stands for Collaborative Processor Performance Controls
and is defined in the ACPI v5.0+ spec. It describes CPU
performance controls on an abstract and continuous scale
allowing the platform (e.g. remote power processor) to flexibly
optimize CPU performance with its knowledge of power budgets
and other architecture specific knowledge.

This patch introduces a CPUFreq driver which works with
existing CPUFreq governors. The backend CPPC methods for
parsing the CPPC table and reading/writing using CPPC semantics
are abstracted away such that they can be used by any other CPPC
based CPUFreq driver in the future.

Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
---
 drivers/cpufreq/Kconfig.arm    |  15 +
 drivers/cpufreq/Makefile       |   1 +
 drivers/cpufreq/cppc_acpi.c    | 801 +++++++++++++++++++++++++++++++++++++++++
 drivers/cpufreq/cppc_acpi.h    | 134 +++++++
 drivers/cpufreq/cppc_cpufreq.c | 186 ++++++++++
 5 files changed, 1137 insertions(+)
 create mode 100644 drivers/cpufreq/cppc_acpi.c
 create mode 100644 drivers/cpufreq/cppc_acpi.h
 create mode 100644 drivers/cpufreq/cppc_cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 0f9a2c3..a977d65 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -255,3 +255,18 @@ config ARM_PXA2xx_CPUFREQ
 	  This add the CPUFreq driver support for Intel PXA2xx SOCs.
 
 	  If in doubt, say N.
+
+config ACPI_CPPC_CPUFREQ
+	tristate "CPUFreq driver based on the ACPI CPPC spec"
+	depends on PCC
+	help
+		This adds a CPUFreq driver which uses CPPC methods
+		as described in the ACPIv5.1 spec. CPPC stands for
+		Collaborative Processor Performance Controls. It
+		is based on an abstract continuous scale of CPU
+		performance values which allows the remote power
+		processor to flexibly optimize for power and
+		performance. CPPC relies on power management firmware
+		for its operation.
+
+		If in doubt, say N.
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index b3ca7b0..a7b0b41 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -76,6 +76,7 @@ obj-$(CONFIG_ARM_SA1110_CPUFREQ)	+= sa1110-cpufreq.o
 obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA_CPUFREQ)		+= tegra-cpufreq.o
 obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
+obj-$(CONFIG_ACPI_CPPC_CPUFREQ) += cppc_cpufreq.o cppc_acpi.o
 
 ##################################################################################
 # PowerPC platform drivers
diff --git a/drivers/cpufreq/cppc_acpi.c b/drivers/cpufreq/cppc_acpi.c
new file mode 100644
index 0000000..0df80af
--- /dev/null
+++ b/drivers/cpufreq/cppc_acpi.c
@@ -0,0 +1,801 @@
+/*
+ * CPPC (Collaborative Processor Performance Control) methods used
+ * by CPUfreq drivers.
+ *
+ * (C) Copyright 2014 Linaro Ltd.
+ * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ *
+ * CPPC describes a few methods for controlling CPU performance using
+ * information from a per CPU table called CPC. This table is described in
+ * the ACPI v5.0+ specification. The table consists of a list of
+ * registers which may be memory mapped or hardware registers and also may
+ * include some static integer values.
+ *
+ * CPU performance is on an abstract continuous scale as against a discretized
+ * P-state scale which is tied to CPU frequency only. In brief, the basic
+ * operation involves:
+ *
+ * - OS makes a CPU performance request. (Can provide min and max bounds)
+ *
+ * - Platform (such as BMC) is free to optimize request within requested bounds
+ *   depending on power/thermal budgets etc.
+ *
+ * - Platform conveys its decision back to OS
+ *
+ * The communication between OS and platform occurs through another medium
+ * called (PCC) Platform Communication Channel. This is a generic mailbox like
+ * mechanism which includes doorbell semantics to indicate register updates.
+ * See drivers/mailbox/pcc.c for details on PCC.
+ *
+ * Finer details about the PCC and CPPC spec are available in the latest
+ * ACPI 5.1 specification.
+ */
+
+#include <linux/cpufreq.h>
+#include <linux/delay.h>
+
+#include "cppc_acpi.h"
+/*
+ * Lock to provide mutually exclusive access to the PCC
+ * channel. e.g. When the remote updates the shared region
+ * with new data, the reader needs to be protected from
+ * other CPUs activity on the same channel.
+ */
+static DEFINE_SPINLOCK(pcc_lock);
+
+static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
+
+/* This layer handles all the PCC specifics for CPPC. */
+static struct mbox_chan *pcc_channel;
+static void __iomem *pcc_comm_addr;
+static u64 comm_base_addr;
+static int pcc_subspace_idx = -1;
+static u16 pcc_cmd_delay;
+
+static int send_pcc_cmd(u16 cmd)
+{
+	int err;
+	struct acpi_pcct_hw_reduced *pcct_ss = pcc_channel->con_priv;
+	struct acpi_pcct_shared_memory *generic_comm_base =
+		(struct acpi_pcct_shared_memory *) pcc_comm_addr;
+	u32 cmd_latency = pcct_ss->latency;
+
+	/* Write to the shared comm region. */
+	writew(cmd, &generic_comm_base->command);
+
+	/* Flip CMD COMPLETE bit */
+	writew(0, &generic_comm_base->status);
+
+	err = mbox_send_message(pcc_channel, &cmd);
+	if (err < 0) {
+		pr_err("Err sending PCC mbox message. cmd = %d, ret = %d\n",
+				cmd, err);
+		return err;
+	}
+
+	/* Wait till platform processes command. */
+	udelay(cmd_latency);
+
+	if (!(readw_relaxed(&generic_comm_base->status)
+		    & PCC_CMD_COMPLETE))
+		mbox_client_txdone(pcc_channel, -EIO);
+	else
+		/* Success */
+		mbox_client_txdone(pcc_channel, 0);
+
+	return 0;
+}
+
+static void cppc_chan_tx_done(struct mbox_client *cl, void *mssg, int ret)
+{
+	if (!ret)
+		pr_debug("CPPC TX completed. CMD sent = %x, ret = %d\n",
+				*(u16 *)mssg, ret);
+	else
+		pr_warn("CPPC TX did not complete: CMD sent = %x, ret = %d\n",
+				*(u16 *)mssg, ret);
+}
+
+struct mbox_client cppc_mbox_cl = {
+	.tx_done = cppc_chan_tx_done,
+	.knows_txdone = true,
+};
+
+/* XXX: Temp adaptation from processor_perflib.c
+ * until we get ACPI CPU idle support on ARM64.
+ */
+
+static int acpi_get_psd(struct cpudata *pr)
+{
+	int result = 0;
+	acpi_status status = AE_OK;
+	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
+	struct acpi_buffer format = {sizeof("NNNNN"), "NNNNN"};
+	struct acpi_buffer state = {0, NULL};
+	union acpi_object  *psd = NULL;
+	struct acpi_psd_package *pdomain;
+	acpi_handle handle;
+	char proc_name[11];
+
+	sprintf(proc_name, "\\_PR.CPU%d", pr->cpu);
+
+	status = acpi_get_handle(NULL, proc_name, &handle);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	status = acpi_evaluate_object(handle, "_PSD", NULL, &buffer);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	psd = buffer.pointer;
+	if (!psd || (psd->type != ACPI_TYPE_PACKAGE)) {
+		pr_err("Invalid _PSD data\n");
+		result = -EFAULT;
+		goto end;
+	}
+
+	if (psd->package.count != 1) {
+		pr_err("Invalid _PSD data\n");
+		result = -EFAULT;
+		goto end;
+	}
+
+	pdomain = &(pr->domain_info);
+
+	state.length = sizeof(struct acpi_psd_package);
+	state.pointer = pdomain;
+
+	status = acpi_extract_package(&(psd->package.elements[0]),
+		&format, &state);
+	if (ACPI_FAILURE(status)) {
+		pr_err("Invalid _PSD data\n");
+		result = -EFAULT;
+		goto end;
+	}
+
+	if (pdomain->num_entries != ACPI_PSD_REV0_ENTRIES) {
+		pr_err("Unknown _PSD:num_entries\n");
+		result = -EFAULT;
+		goto end;
+	}
+
+	if (pdomain->revision != ACPI_PSD_REV0_REVISION) {
+		pr_err("Unknown _PSD:revision\n");
+		result = -EFAULT;
+		goto end;
+	}
+
+	if (pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ALL &&
+	    pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ANY &&
+	    pdomain->coord_type != DOMAIN_COORD_TYPE_HW_ALL) {
+		pr_err("Invalid _PSD:coord_type\n");
+		result = -EFAULT;
+		goto end;
+	}
+end:
+	kfree(buffer.pointer);
+	return result;
+}
+
+/* XXX: Temp adaptation from processor_perflib.c
+ * until we get ACPI CPU idle support on ARM64.
+ */
+int acpi_get_psd_map(struct cpudata **all_cpu_data)
+{
+	int count_target;
+	int retval = 0;
+	unsigned int i, j;
+	cpumask_var_t covered_cpus;
+	struct cpudata *pr;
+	struct acpi_psd_package *pdomain;
+	struct cpudata *match_pr;
+	struct acpi_psd_package *match_pdomain;
+
+	if (!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))
+		return -ENOMEM;
+
+	/* Call _PSD for all CPUs */
+	for_each_online_cpu(i) {
+		pr = all_cpu_data[i];
+		if (!pr)
+			continue;
+
+		if (!zalloc_cpumask_var_node(&pr->shared_cpu_map,
+					GFP_KERNEL, cpu_to_node(pr->cpu))) {
+			pr_err("No mem for shared_cpus cpumask\n");
+			return -ENOMEM;
+		}
+
+		cpumask_set_cpu(i, pr->shared_cpu_map);
+		if (acpi_get_psd(pr)) {
+			retval = -EINVAL;
+			continue;
+		}
+	}
+	if (retval)
+		goto err_ret;
+
+	/*
+	 * Now that we have _PSD data from all CPUs, lets setup P-state
+	 * domain info.
+	 */
+	for_each_online_cpu(i) {
+		pr = all_cpu_data[i];
+		if (!pr)
+			continue;
+
+		if (cpumask_test_cpu(i, covered_cpus))
+			continue;
+
+		pdomain = &(pr->domain_info);
+		cpumask_set_cpu(i, pr->shared_cpu_map);
+		cpumask_set_cpu(i, covered_cpus);
+		if (pdomain->num_processors <= 1)
+			continue;
+
+		/* Validate the Domain info */
+		count_target = pdomain->num_processors;
+		if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
+			pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
+		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
+			pr->shared_type = CPUFREQ_SHARED_TYPE_HW;
+		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
+			pr->shared_type = CPUFREQ_SHARED_TYPE_ANY;
+
+		for_each_online_cpu(j) {
+			if (i == j)
+				continue;
+
+			match_pr = all_cpu_data[j];
+			if (!match_pr)
+				continue;
+
+			match_pdomain = &(match_pr->domain_info);
+			if (match_pdomain->domain != pdomain->domain)
+				continue;
+
+			/* Here i and j are in the same domain */
+
+			if (match_pdomain->num_processors != count_target) {
+				retval = -EINVAL;
+				goto err_ret;
+			}
+
+			if (pdomain->coord_type != match_pdomain->coord_type) {
+				retval = -EINVAL;
+				goto err_ret;
+			}
+
+			cpumask_set_cpu(j, covered_cpus);
+			cpumask_set_cpu(j, pr->shared_cpu_map);
+		}
+
+		for_each_online_cpu(j) {
+			if (i == j)
+				continue;
+
+			match_pr = all_cpu_data[j];
+			if (!match_pr)
+				continue;
+
+			match_pdomain = &(match_pr->domain_info);
+			if (match_pdomain->domain != pdomain->domain)
+				continue;
+
+			match_pr->shared_type =
+					pr->shared_type;
+			cpumask_copy(match_pr->shared_cpu_map,
+				     pr->shared_cpu_map);
+		}
+	}
+
+err_ret:
+	for_each_online_cpu(i) {
+		pr = all_cpu_data[i];
+		if (!pr)
+			continue;
+
+		/* Assume no coordination on any error parsing domain info */
+		if (retval) {
+			cpumask_clear(pr->shared_cpu_map);
+			cpumask_set_cpu(i, pr->shared_cpu_map);
+			pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
+		}
+	}
+
+	free_cpumask_var(covered_cpus);
+	return retval;
+}
+EXPORT_SYMBOL(acpi_get_psd_map);
+
+/**
+ * acpi_cppc_processor_probe -
+ * The _CPC table is a per CPU table which a bunch of entries which
+ * may be registers or integers.
+ * An example table looks like the following.
+ *
+ *	Name(_CPC, Package()
+ *			{
+ *			17,
+ *			NumEntries
+ *			1,
+ *			// Revision
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x120, 2)},
+ *			// Highest Performance
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x124, 2)},
+ *			// Nominal Performance
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x128, 2)},
+ *			// Lowest Nonlinear Performance
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x12C, 2)},
+ *			// Lowest Performance
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x130, 2)},
+ *			// Guaranteed Performance Register
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x110, 2)},
+ *			// Desired Performance Register
+ *			ResourceTemplate(){Register(SystemMemory, 0, 0, 0, 0)},
+ *			..
+ *			..
+ *			..
+ *
+ *		}
+ * Each Register() encodes how to access that specific register.
+ * e.g. a sample PCC entry has the following encoding:
+ *
+ *	Register (
+ *		PCC,
+ *		AddressSpaceKeyword
+ *		8,
+ *		//RegisterBitWidth
+ *		8,
+ *		//RegisterBitOffset
+ *		0x30,
+ *		//RegisterAddress
+ *		9
+ *		//AccessSize (subspace ID)
+ *		0
+ *		)
+ *		}
+ *
+ *	This function walks through all the per CPU _CPC entries and extracts
+ *	the Register details.
+ *
+ *	Return: 0 for success or negative value for err.
+ */
+int acpi_cppc_processor_probe(void)
+{
+	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
+	union acpi_object *out_obj, *cpc_obj;
+	struct cpc_desc *current_cpu_cpc;
+	struct cpc_reg *gas_t;
+	struct acpi_pcct_subspace *cppc_ss;
+	char proc_name[11];
+	unsigned int num_ent, ret = 0, i, cpu, len;
+	acpi_handle handle;
+	acpi_status status;
+
+	/* Parse the ACPI _CPC table for each cpu. */
+	for_each_online_cpu(cpu) {
+		sprintf(proc_name, "\\_PR.CPU%d", cpu);
+
+		status = acpi_get_handle(NULL, proc_name, &handle);
+		if (ACPI_FAILURE(status)) {
+			ret = -ENODEV;
+			goto out_free;
+		}
+
+		if (!acpi_has_method(handle, "_CPC")) {
+			ret = -ENODEV;
+			goto out_free;
+		}
+
+		status = acpi_evaluate_object(handle, "_CPC", NULL, &output);
+		if (ACPI_FAILURE(status)) {
+			ret = -ENODEV;
+			goto out_free;
+		}
+
+		out_obj = (union acpi_object *) output.pointer;
+		if (out_obj->type != ACPI_TYPE_PACKAGE) {
+			ret = -ENODEV;
+			goto out_free;
+		}
+
+		current_cpu_cpc = kzalloc(sizeof(struct cpc_desc), GFP_KERNEL);
+		if (!current_cpu_cpc)
+			return -ENOMEM;
+
+		num_ent = out_obj->package.count;
+
+		pr_debug("num_ent in CPC table:%d\n", num_ent);
+
+		/* Iterate through each entry in _CPC */
+		for (i = 2; i < num_ent; i++) {
+			cpc_obj = &out_obj->package.elements[i];
+
+			if (cpc_obj->type == ACPI_TYPE_INTEGER)	{
+				current_cpu_cpc->cpc_regs[i-2].type =
+					ACPI_TYPE_INTEGER;
+				current_cpu_cpc->cpc_regs[i-2].cpc_entry.int_value =
+					cpc_obj->integer.value;
+			} else if (cpc_obj->type == ACPI_TYPE_BUFFER) {
+				gas_t = (struct cpc_reg *)
+					cpc_obj->buffer.pointer;
+
+				/*
+				 * The PCC Subspace index is encoded inside
+				 * the CPC table entries. The same PCC index
+				 * will be used for all the PCC entries,
+				 * so extract it only once.
+				 */
+				if (gas_t->space_id ==
+						ACPI_ADR_SPACE_PLATFORM_COMM) {
+					if (pcc_subspace_idx < 0)
+						pcc_subspace_idx =
+							gas_t->access_width;
+				}
+
+				/*
+				 * First two entires are Version and num of
+				 * entries. Rest of them are registers or
+				 * ints. Hence the loop begins at 2.
+				 * Get each reg info.
+				 */
+				current_cpu_cpc->cpc_regs[i-2].type =
+					ACPI_TYPE_BUFFER;
+				current_cpu_cpc->cpc_regs[i-2].cpc_entry.reg =
+					(struct cpc_reg) {
+						.space_id = gas_t->space_id,
+						.length	= gas_t->length,
+						.bit_width = gas_t->bit_width,
+						.bit_offset = gas_t->bit_offset,
+						.address = gas_t->address,
+						.access_width =
+							gas_t->access_width,
+					};
+			} else {
+				pr_err("Error in entry:%d in CPC table.\n", i);
+				ret = -EINVAL;
+				goto out_free;
+			}
+		}
+
+		/* Plug it into this CPUs CPC descriptor. */
+		per_cpu(cpc_desc_ptr, cpu) = current_cpu_cpc;
+	}
+
+	/*
+	 * Now that we have all the information from the CPC table,
+	 * lets get a mailbox channel from the mailbox controller.
+	 * The channel for client is indexed using the subspace id
+	 * which was encoded in the Register(PCC.. entries.
+	 */
+	pr_debug("Completed parsing, now onto PCC init\n");
+
+	if (pcc_subspace_idx >= 0) {
+		pcc_channel = pcc_mbox_request_channel(&cppc_mbox_cl,
+				pcc_subspace_idx);
+
+		if (IS_ERR(pcc_channel)) {
+			pr_err("No PCC communication channel found\n");
+			ret = -ENODEV;
+			goto out_free;
+		}
+
+
+		/*
+		 * The PCC mailbox controller driver should
+		 * have parsed the PCCT (global table of all
+		 * PCC channels) and stored pointers to the
+		 * subspace communication region in con_priv.
+		 */
+		cppc_ss = pcc_channel->con_priv;
+
+		if (!cppc_ss) {
+			pr_err("No PCC subspace found for CPPC\n");
+			ret = -ENODEV;
+			goto out_free;
+		}
+
+		/*
+		 * This is the shared communication region
+		 * for the OS and Platform to communicate over.
+		 */
+		comm_base_addr = cppc_ss->base_address;
+		len = cppc_ss->length;
+		pcc_cmd_delay = cppc_ss->min_turnaround_time;
+
+		pr_debug("From PCCT: CPPC subspace addr:%llx, len: %d\n",
+				comm_base_addr, len);
+		pcc_comm_addr = ioremap(comm_base_addr, len);
+		if (!pcc_comm_addr) {
+			ret = -ENOMEM;
+			pr_err("Failed to ioremap PCC comm region mem\n");
+			goto out_free;
+		}
+
+		pr_debug("New PCC comm space addr: %llx\n", (u64)pcc_comm_addr);
+
+	} else
+		/* For the case where registers are not defined as PCC regs. */
+		pr_warn("No PCC subspace detected in any CPC entries.\n");
+
+	/* Everything looks okay */
+	pr_info("Successfully parsed all CPC structs\n");
+
+	kfree(output.pointer);
+	return 0;
+
+out_free:
+	for_each_online_cpu(cpu) {
+		current_cpu_cpc = per_cpu(cpc_desc_ptr, cpu);
+		kfree(current_cpu_cpc);
+	}
+
+	kfree(output.pointer);
+	return -ENODEV;
+}
+EXPORT_SYMBOL(acpi_cppc_processor_probe);
+
+static u64 cpc_trans(struct cpc_register_resource *reg, int cmd, u64 write_val,
+		bool is_pcc)
+{
+	u64 addr;
+	u64 read_val = 0;
+
+	/* PCC communication addr space begins at byte offset 0x8. */
+	if (is_pcc == true)
+		addr = (u64)pcc_comm_addr + 0x8 + reg->cpc_entry.reg.address;
+	else
+		addr = reg->cpc_entry.reg.address;
+
+	if (reg->type == ACPI_TYPE_BUFFER) {
+		switch (reg->cpc_entry.reg.bit_width) {
+		case 8:
+			if (cmd == CMD_READ)
+				read_val = readb((void *) (addr));
+			else if (cmd == CMD_WRITE)
+				writeb(write_val, (void *)(addr));
+			else
+				pr_err("Unsupported cmd type: %d\n", cmd);
+			break;
+		case 16:
+			if (cmd == CMD_READ)
+				read_val = readw((void *) (addr));
+			else if (cmd == CMD_WRITE)
+				writew(write_val, (void *)(addr));
+			else
+				pr_err("Unsupported cmd type: %d\n", cmd);
+			break;
+		case 32:
+			if (cmd == CMD_READ)
+				read_val = readl((void *) (addr));
+			else if (cmd == CMD_WRITE)
+				writel(write_val, (void *)(addr));
+			else
+				pr_err("Unsupported cmd type: %d\n", cmd);
+			break;
+		case 64:
+			if (cmd == CMD_READ)
+				read_val = readq((void *) (addr));
+			else if (cmd == CMD_WRITE)
+				writeq(write_val, (void *)(addr));
+			else
+				pr_err("Unsupported cmd type: %d\n", cmd);
+			break;
+		default:
+			pr_err("Unsupported bit width for CPC read/write (cmd:%d)\n",
+					cmd);
+			break;
+		}
+	} else if (reg->type == ACPI_TYPE_INTEGER) {
+		if (cmd == CMD_READ)
+			read_val = reg->cpc_entry.int_value;
+		else if (cmd == CMD_WRITE)
+			reg->cpc_entry.int_value = write_val;
+		else
+			pr_err("Unsupported cmd type: %d\n", cmd);
+	} else
+		pr_err("Unsupported CPC entry type :%d\n", reg->type);
+
+	return read_val;
+}
+
+/**
+ * cppc_get_perf_caps - Get a CPUs performance capabilities.
+ * @cpunum: CPU from which to get capabilities info.
+ * @perf_caps: ptr to cppc_perf_caps. See cppc_acpi.h
+ *
+ * Return - 0 for success with perf_caps populated else
+ *	-ERRNO.
+ */
+int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+	struct cpc_register_resource *highest_reg, *lowest_reg, *ref_perf,
+				     *nom_perf;
+	u64 min, max, ref, nom;
+	bool is_pcc = false;
+
+	if (!cpc_desc) {
+		pr_err("No CPC descriptor for CPU:%d\n", cpunum);
+		return -ENODEV;
+	}
+
+	highest_reg = &cpc_desc->cpc_regs[HIGHEST_PERF];
+	lowest_reg = &cpc_desc->cpc_regs[LOWEST_PERF];
+	ref_perf = &cpc_desc->cpc_regs[REFERENCE_PERF];
+	nom_perf = &cpc_desc->cpc_regs[NOMINAL_PERF];
+
+	spin_lock(&pcc_lock);
+
+	/* Are any of the regs PCC ?*/
+	if ((highest_reg->cpc_entry.reg.space_id ==
+				ACPI_ADR_SPACE_PLATFORM_COMM) ||
+			(lowest_reg->cpc_entry.reg.space_id ==
+			 ACPI_ADR_SPACE_PLATFORM_COMM) ||
+			(ref_perf->cpc_entry.reg.space_id ==
+			 ACPI_ADR_SPACE_PLATFORM_COMM) ||
+			(nom_perf->cpc_entry.reg.space_id ==
+			 ACPI_ADR_SPACE_PLATFORM_COMM))
+		is_pcc = true;
+
+	if (is_pcc == true) {
+		/*
+		 * Min time OS should wait before sending
+		 * next command.
+		 */
+		udelay(pcc_cmd_delay);
+		/* Ring doorbell */
+		send_pcc_cmd(CMD_READ);
+	}
+
+	max = cpc_trans(highest_reg, CMD_READ, 0, is_pcc);
+	perf_caps->highest_perf = max;
+
+	min = cpc_trans(lowest_reg, CMD_READ, 0, is_pcc);
+	perf_caps->lowest_perf = min;
+
+	ref = cpc_trans(ref_perf, CMD_READ, 0, is_pcc);
+	perf_caps->reference_perf = ref;
+
+	pr_err("Ref perf: %d\n", perf_caps->reference_perf);
+
+	nom = cpc_trans(nom_perf, CMD_READ, 0, is_pcc);
+	perf_caps->nominal_perf = nom;
+
+	pr_err("Nom perf: %d\n", perf_caps->nominal_perf);
+
+	if (!ref)
+		perf_caps->reference_perf = perf_caps->nominal_perf;
+
+	spin_unlock(&pcc_lock);
+
+	if (!perf_caps->highest_perf ||
+			!perf_caps->lowest_perf ||
+			!perf_caps->reference_perf ||
+			!perf_caps->nominal_perf) {
+		pr_err("Err reading CPU performance limits\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(cppc_get_perf_caps);
+
+/**
+ * cppc_get_perf_ctrs - Read a CPUs performance feedback counters.
+ * @cpunum: CPU from which to read counters.
+ * @perf_fb_ctrs: ptr to cppc_perf_fb_ctrs. See cppc_acpi.h
+ *
+ * Return - 0 for success with perf_fb_ctrs populated else
+ *	-ERRNO.
+ */
+int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+	struct cpc_register_resource *delivered_reg, *reference_reg;
+	u64 delivered, reference;
+	bool is_pcc = false;
+
+	if (!cpc_desc) {
+		pr_err("No CPC descriptor for CPU:%d\n", cpunum);
+		return -ENODEV;
+	}
+
+	delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];
+	reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];
+
+	spin_lock(&pcc_lock);
+
+	/* Are any of the regs PCC ?*/
+	if ((delivered_reg->cpc_entry.reg.space_id ==
+				ACPI_ADR_SPACE_PLATFORM_COMM) ||
+			(reference_reg->cpc_entry.reg.space_id ==
+			 ACPI_ADR_SPACE_PLATFORM_COMM))
+		is_pcc = true;
+
+	if (is_pcc == true) {
+		/*
+		 * Min time OS should wait before sending
+		 * next command.
+		 */
+		udelay(pcc_cmd_delay);
+		/* Ring doorbell */
+		send_pcc_cmd(CMD_READ);
+	}
+
+	delivered = cpc_trans(delivered_reg, CMD_READ, 0, is_pcc);
+	reference = cpc_trans(reference_reg, CMD_READ, 0, is_pcc);
+
+	spin_unlock(&pcc_lock);
+
+	if (!delivered || !reference) {
+		pr_err("Bogus values from Delivered or Reference counters\n");
+		return -EINVAL;
+	}
+
+	perf_fb_ctrs->delivered = delivered;
+	perf_fb_ctrs->reference = reference;
+
+	perf_fb_ctrs->delivered -= perf_fb_ctrs->prev_delivered;
+	perf_fb_ctrs->reference -= perf_fb_ctrs->prev_reference;
+
+	perf_fb_ctrs->prev_delivered = delivered;
+	perf_fb_ctrs->prev_reference = reference;
+
+	return 0;
+}
+EXPORT_SYMBOL(cppc_get_perf_ctrs);
+
+/**
+ * cppc_set_perf - Set a CPUs performance controls.
+ * @cpu: CPU for which to set performance controls.
+ * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
+ *
+ * Return: 0 for success, -ERRNO otherwise.
+ */
+int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
+	struct cpc_register_resource *desired_reg;
+	int ret = 0;
+	bool is_pcc = false;
+
+	if (!cpc_desc) {
+		pr_err("No CPC descriptor for CPU:%d\n", cpu);
+		return -ENODEV;
+	}
+
+	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+
+	spin_lock(&pcc_lock);
+
+	/* Is this a PCC reg ?*/
+	if (desired_reg->cpc_entry.reg.space_id ==
+			ACPI_ADR_SPACE_PLATFORM_COMM)
+		is_pcc = true;
+
+	cpc_trans(desired_reg, CMD_WRITE,
+			perf_ctrls->desired_perf, is_pcc);
+
+	if (is_pcc == true) {
+		/*
+		 * Min time OS should wait before sending
+		 * next command.
+		 */
+		udelay(pcc_cmd_delay);
+		/* Ring doorbell */
+		send_pcc_cmd(CMD_READ);
+	}
+
+	spin_unlock(&pcc_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(cppc_set_perf);
+
diff --git a/drivers/cpufreq/cppc_acpi.h b/drivers/cpufreq/cppc_acpi.h
new file mode 100644
index 0000000..a6c7ff6
--- /dev/null
+++ b/drivers/cpufreq/cppc_acpi.h
@@ -0,0 +1,134 @@
+/*
+ * CPPC (Collaborative Processor Performance Control) methods used
+ * by CPUfreq drivers.
+ *
+ * (C) Copyright 2014 Linaro Ltd.
+ * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#ifndef _CPPC_ACPI_H
+#define _CPPC_ACPI_H
+
+#include <linux/acpi.h>
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
+#include <linux/types.h>
+
+#include <acpi/processor.h>
+
+#define PCC_CMD_COMPLETE 1
+#define MAX_CPC_REG_ENT 19
+
+/* CPPC specific PCC commands. */
+#define	CMD_READ 0
+#define	CMD_WRITE 1
+
+/* Each register has the folowing format. */
+struct cpc_reg {
+	u8 descriptor;
+	u16 length;
+	u8 space_id;
+	u8 bit_width;
+	u8 bit_offset;
+	u8 access_width;
+	u64 __iomem address;
+} __packed;
+
+/*
+ * Each entry in the CPC table is either
+ * of type ACPI_TYPE_BUFFER or
+ * ACPI_TYPE_INTEGER.
+ */
+struct cpc_register_resource {
+	acpi_object_type type;
+	union {
+		struct cpc_reg reg;
+		u64 int_value;
+	} cpc_entry;
+};
+
+/* Container to hold the CPC details for each CPU */
+struct cpc_desc {
+	int num_entries;
+	int version;
+	struct cpc_register_resource cpc_regs[MAX_CPC_REG_ENT];
+};
+
+/* These are indexes into the per-cpu cpc_regs[]. Order is important. */
+enum cppc_regs {
+	HIGHEST_PERF,
+	NOMINAL_PERF,
+	LOW_NON_LINEAR_PERF,
+	LOWEST_PERF,
+	GUARANTEED_PERF,
+	DESIRED_PERF,
+	MIN_PERF,
+	MAX_PERF,
+	PERF_REDUC_TOLERANCE,
+	TIME_WINDOW,
+	CTR_WRAP_TIME,
+	REFERENCE_CTR,
+	DELIVERED_CTR,
+	PERF_LIMITED,
+	ENABLE,
+	AUTO_SEL_ENABLE,
+	AUTO_ACT_WINDOW,
+	ENERGY_PERF,
+	REFERENCE_PERF,
+};
+
+/*
+ * Categorization of registers as described
+ * in the ACPI v.5.1 spec.
+ * XXX: Only filling up ones which are used by governors
+ * today.
+ */
+struct cppc_perf_caps {
+	u32 highest_perf;
+	u32 nominal_perf;
+	u32 reference_perf;
+	u32 lowest_perf;
+};
+
+struct cppc_perf_ctrls {
+	u32 max_perf;
+	u32 min_perf;
+	u32 desired_perf;
+};
+
+struct cppc_perf_fb_ctrs {
+	u64 reference;
+	u64 prev_reference;
+	u64 delivered;
+	u64 prev_delivered;
+};
+
+/* Per CPU container for runtime CPPC management. */
+struct cpudata {
+	int cpu;
+	struct cppc_perf_caps perf_caps;
+	struct cppc_perf_ctrls perf_ctrls;
+	struct cppc_perf_fb_ctrs perf_fb_ctrs;
+	struct cpufreq_policy *cur_policy;
+	struct acpi_psd_package domain_info;
+	unsigned int shared_type;
+	cpumask_var_t shared_cpu_map;
+};
+
+extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
+extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
+extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps);
+extern int acpi_get_psd_map(struct cpudata **);
+extern int acpi_cppc_processor_probe(void);
+
+/* Methods to interact with the PCC mailbox controller. */
+extern struct mbox_chan *
+	pcc_mbox_request_channel(struct mbox_client *, unsigned int);
+extern int mbox_send_message(struct mbox_chan *chan, void *mssg);
+
+#endif /* _CPPC_ACPI_H*/
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
new file mode 100644
index 0000000..258e27f1
--- /dev/null
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -0,0 +1,186 @@
+/*
+ * CPPC (Collaborative Processor Performance Control) driver for
+ * interfacing with the CPUfreq layer and governors. See
+ * cppc_acpi.c for CPPC specific methods.
+ *
+ * (C) Copyright 2014 Linaro Ltd.
+ * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/vmalloc.h>
+
+#include "cppc_acpi.h"
+
+static struct cpudata **all_cpu_data;
+
+static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
+		unsigned int target_freq,
+		unsigned int relation)
+{
+	struct cpudata *cpu;
+	struct cpufreq_freqs freqs;
+	int ret;
+
+	cpu = all_cpu_data[policy->cpu];
+
+	cpu->perf_ctrls.desired_perf = target_freq;
+	freqs.old = policy->cur;
+	freqs.new = target_freq;
+
+	cpufreq_freq_transition_begin(policy, &freqs);
+	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
+	cpufreq_freq_transition_end(policy, &freqs, ret != 0);
+
+	if (ret) {
+		pr_debug("Failed to set target on CPU:%d\n", cpu->cpu);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static unsigned int cppc_cpufreq_get_perf(unsigned int cpu_num)
+{
+	struct cpudata *cpu;
+	int32_t delivered_perf = 1;
+
+	cpu = all_cpu_data[cpu_num];
+	if (!cpu)
+		return 0;
+
+	cppc_get_perf_ctrs(cpu_num, &cpu->perf_fb_ctrs);
+
+	delivered_perf = cpu->perf_caps.reference_perf *
+		cpu->perf_fb_ctrs.delivered;
+	delivered_perf /= cpu->perf_fb_ctrs.reference;
+	pr_debug("delivered_perf: %d\n", delivered_perf);
+	pr_debug("reference_perf: %d\n",
+			cpu->perf_caps.reference_perf);
+	pr_debug("delivered, reference deltas: %lld, %lld\n",
+			cpu->perf_fb_ctrs.delivered,
+			cpu->perf_fb_ctrs.reference);
+
+	return delivered_perf;
+}
+
+static int cppc_verify_policy(struct cpufreq_policy *policy)
+{
+	cpufreq_verify_within_cpu_limits(policy);
+	return 0;
+}
+
+static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
+{
+	int cpu_num = policy->cpu;
+	struct cpudata *cpu = all_cpu_data[cpu_num];
+	int ret;
+
+	pr_info("CPPC ondemand CPU %d exiting\n", cpu_num);
+
+	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
+
+	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
+	if (ret)
+		pr_err("Err setting perf value:%d on CPU:%d\n",
+				cpu->perf_caps.lowest_perf, cpu_num);
+}
+
+static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+	struct cpudata *cpu;
+	int ret;
+
+	cpu = all_cpu_data[policy->cpu];
+
+	cpu->cpu = policy->cpu;
+	ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
+
+	if (ret) {
+		pr_err("Err reading CPU%d, perf capabilities\n", cpu->cpu);
+		return -ENODEV;
+	}
+
+	policy->min = cpu->perf_caps.lowest_perf;
+	policy->max = cpu->perf_caps.highest_perf;
+	/* cpuinfo and default policy values */
+	policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf;
+	policy->cpuinfo.max_freq = cpu->perf_caps.highest_perf;
+
+	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL ||
+	    policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
+		cpumask_copy(policy->cpus, cpu->shared_cpu_map);
+
+	cpumask_set_cpu(policy->cpu, policy->cpus);
+	cpu->cur_policy = policy;
+
+	return 0;
+}
+
+static struct cpufreq_driver cppc_cpufreq_driver = {
+	.flags = CPUFREQ_CONST_LOOPS,
+	.verify = cppc_verify_policy,
+	.target = cppc_cpufreq_set_target,
+	.get = cppc_cpufreq_get_perf,
+	.init = cppc_cpufreq_cpu_init,
+	.stop_cpu = cppc_cpufreq_stop_cpu,
+	.name = "cppc_cpufreq",
+};
+
+static int __init cppc_cpufreq_init(void)
+{
+	int cpu, rc = 0;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	if (acpi_cppc_processor_probe()) {
+		pr_err("Err initializing CPC structures\n");
+		return -ENODEV;
+	}
+
+	pr_info("ACPI CPPC CPUFreq driver initializing.\n");
+
+	all_cpu_data = vzalloc(sizeof(void *) * num_possible_cpus());
+	if (!all_cpu_data)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		all_cpu_data[cpu] = kzalloc(sizeof(struct cpudata), GFP_KERNEL);
+		if (!all_cpu_data[cpu])
+			return -ENOMEM;
+	}
+
+	rc = acpi_get_psd_map(all_cpu_data);
+	if (rc) {
+		pr_err("Err parsing PSD data\n");
+		goto out;
+	}
+
+	rc = cpufreq_register_driver(&cppc_cpufreq_driver);
+	if (rc)
+		goto out;
+
+	return rc;
+
+out:
+	get_online_cpus();
+	for_each_online_cpu(cpu)
+		if (all_cpu_data[cpu])
+			kfree(all_cpu_data[cpu]);
+
+	put_online_cpus();
+	vfree(all_cpu_data);
+	return -ENODEV;
+}
+
+late_initcall(cppc_cpufreq_init);
-- 
1.9.1

Re: [PATCH v4 2/2] CPPC: Add CPUFreq driver based on CPPC methods

[Rafael J. Wysocki]

On Tuesday, January 27, 2015 04:03:58 PM Ashwin Chaugule wrote:
> CPPC stands for Collaborative Processor Performance Controls
> and is defined in the ACPI v5.0+ spec. It describes CPU
> performance controls on an abstract and continuous scale
> allowing the platform (e.g. remote power processor) to flexibly
> optimize CPU performance with its knowledge of power budgets
> and other architecture specific knowledge.
> 
> This patch introduces a CPUFreq driver which works with
> existing CPUFreq governors. The backend CPPC methods for
> parsing the CPPC table and reading/writing using CPPC semantics
> are abstracted away such that they can be used by any other CPPC
> based CPUFreq driver in the future.

First question: How do we ensure that this won't interact negatively with
the existing ACPI cpufreq driver?  In particular, what is there to allow
users to use the driver they want?


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH v4 2/2] CPPC: Add CPUFreq driver based on CPPC methods

[Ashwin Chaugule]

Hi Rafael,

On 3 February 2015 at 17:33, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Tuesday, January 27, 2015 04:03:58 PM Ashwin Chaugule wrote:
>> CPPC stands for Collaborative Processor Performance Controls
>> and is defined in the ACPI v5.0+ spec. It describes CPU
>> performance controls on an abstract and continuous scale
>> allowing the platform (e.g. remote power processor) to flexibly
>> optimize CPU performance with its knowledge of power budgets
>> and other architecture specific knowledge.
>>
>> This patch introduces a CPUFreq driver which works with
>> existing CPUFreq governors. The backend CPPC methods for
>> parsing the CPPC table and reading/writing using CPPC semantics
>> are abstracted away such that they can be used by any other CPPC
>> based CPUFreq driver in the future.
>
> First question: How do we ensure that this won't interact negatively with
> the existing ACPI cpufreq driver?  In particular, what is there to allow
> users to use the driver they want?

The existing ACPI cpufreq driver isnt enabled on ARM. (At a minimum,
it needs spec updates in the PSS sections for ARM.) For ARM64 servers,
CPPC is the preferred choice. But you're right, if someone adds PSS
support on ARM then we need a way to make these two mutually exclusive
at runtime. IIUC on X86, intel_pstate is skipped if it finds PSS/PPC?
On ARM64 servers, we'd want it the other way. i.e. if the acpi-cpufreq
driver detects CPC then it skips its init. I'm open to any suggestions
on how to handle this.

Thanks,
Ashwin

Re: [PATCH v4 2/2] CPPC: Add CPUFreq driver based on CPPC methods

[Rafael J. Wysocki]

On Tuesday, February 03, 2015 10:23:31 PM Ashwin Chaugule wrote:
> Hi Rafael,
> 
> On 3 February 2015 at 17:33, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > On Tuesday, January 27, 2015 04:03:58 PM Ashwin Chaugule wrote:
> >> CPPC stands for Collaborative Processor Performance Controls
> >> and is defined in the ACPI v5.0+ spec. It describes CPU
> >> performance controls on an abstract and continuous scale
> >> allowing the platform (e.g. remote power processor) to flexibly
> >> optimize CPU performance with its knowledge of power budgets
> >> and other architecture specific knowledge.
> >>
> >> This patch introduces a CPUFreq driver which works with
> >> existing CPUFreq governors. The backend CPPC methods for
> >> parsing the CPPC table and reading/writing using CPPC semantics
> >> are abstracted away such that they can be used by any other CPPC
> >> based CPUFreq driver in the future.
> >
> > First question: How do we ensure that this won't interact negatively with
> > the existing ACPI cpufreq driver?  In particular, what is there to allow
> > users to use the driver they want?
> 
> The existing ACPI cpufreq driver isnt enabled on ARM. (At a minimum,
> it needs spec updates in the PSS sections for ARM.) For ARM64 servers,
> CPPC is the preferred choice. But you're right, if someone adds PSS
> support on ARM then we need a way to make these two mutually exclusive
> at runtime.

Analogously, if _CPC is present on a non-ARM platform.

> IIUC on X86, intel_pstate is skipped if it finds PSS/PPC?

Nope.  There are quirks for systems where this happens, but generally
intel_pstate is a preferred driver.

> On ARM64 servers, we'd want it the other way. i.e. if the acpi-cpufreq
> driver detects CPC then it skips its init.

I'm not sure if we can do that in general, though.

> I'm open to any suggestions on how to handle this.

Let me think about that a bit more.


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH v4 2/2] CPPC: Add CPUFreq driver based on CPPC methods

[Ashwin Chaugule]

Hello,

On 4 February 2015 at 09:33, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Tuesday, February 03, 2015 10:23:31 PM Ashwin Chaugule wrote:
>> On 3 February 2015 at 17:33, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>> > On Tuesday, January 27, 2015 04:03:58 PM Ashwin Chaugule wrote:
>> >
>> > First question: How do we ensure that this won't interact negatively with
>> > the existing ACPI cpufreq driver?  In particular, what is there to allow
>> > users to use the driver they want?
>>
>> The existing ACPI cpufreq driver isnt enabled on ARM. (At a minimum,
>> it needs spec updates in the PSS sections for ARM.) For ARM64 servers,
>> CPPC is the preferred choice. But you're right, if someone adds PSS
>> support on ARM then we need a way to make these two mutually exclusive
>> at runtime.
>
> Analogously, if _CPC is present on a non-ARM platform.

Hm. Currently CPPC is available only under Kconfig.arm under cpufreq.
My understanding is that X86 will use HWP (CPPC equivalent) through
intel_pstate (using MSRs). I'm not aware of any other non-ARM platform
that could use this as of yet, although in theory, any platform with
ACPI support should be able to.

>> On ARM64 servers, we'd want it the other way. i.e. if the acpi-cpufreq
>> driver detects CPC then it skips its init.
>
> I'm not sure if we can do that in general, though.

Curious to know why we couldn't check for _CPC in the acpi-cpufreq
driver and bail if it is found? FWIW, the spec also states that if
_CPC is present it supersedes _PSS and friends  (section 8.4.5.1.10)

>
>> I'm open to any suggestions on how to handle this.
>
> Let me think about that a bit more.

Much appreciated!

Cheers,
Ashwin

Re: [PATCH v4 2/2] CPPC: Add CPUFreq driver based on CPPC methods

[Ashwin Chaugule]

Hi Rafael,

On 4 February 2015 at 10:18, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote:
> Hello,
>
> On 4 February 2015 at 09:33, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>> On Tuesday, February 03, 2015 10:23:31 PM Ashwin Chaugule wrote:
>>> On 3 February 2015 at 17:33, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>>> > On Tuesday, January 27, 2015 04:03:58 PM Ashwin Chaugule wrote:
>>> >
>>> > First question: How do we ensure that this won't interact negatively with
>>> > the existing ACPI cpufreq driver?  In particular, what is there to allow
>>> > users to use the driver they want?
>>>
>>> The existing ACPI cpufreq driver isnt enabled on ARM. (At a minimum,
>>> it needs spec updates in the PSS sections for ARM.) For ARM64 servers,
>>> CPPC is the preferred choice. But you're right, if someone adds PSS
>>> support on ARM then we need a way to make these two mutually exclusive
>>> at runtime.
>>
>> Analogously, if _CPC is present on a non-ARM platform.
>
> Hm. Currently CPPC is available only under Kconfig.arm under cpufreq.
> My understanding is that X86 will use HWP (CPPC equivalent) through
> intel_pstate (using MSRs). I'm not aware of any other non-ARM platform
> that could use this as of yet, although in theory, any platform with
> ACPI support should be able to.
>
>>> On ARM64 servers, we'd want it the other way. i.e. if the acpi-cpufreq
>>> driver detects CPC then it skips its init.
>>
>> I'm not sure if we can do that in general, though.
>
> Curious to know why we couldn't check for _CPC in the acpi-cpufreq
> driver and bail if it is found? FWIW, the spec also states that if
> _CPC is present it supersedes _PSS and friends  (section 8.4.5.1.10)
>
>>
>>> I'm open to any suggestions on how to handle this.
>>
>> Let me think about that a bit more.
>
> Much appreciated!

Gentle reminder to review the CPPC patch.

Thanks,
Ashwin.

Re: [PATCH v4 2/2] CPPC: Add CPUFreq driver based on CPPC methods

[Rafael J. Wysocki]

On Tuesday, January 27, 2015 04:03:58 PM Ashwin Chaugule wrote:
> CPPC stands for Collaborative Processor Performance Controls
> and is defined in the ACPI v5.0+ spec. It describes CPU
> performance controls on an abstract and continuous scale
> allowing the platform (e.g. remote power processor) to flexibly
> optimize CPU performance with its knowledge of power budgets
> and other architecture specific knowledge.
> 
> This patch introduces a CPUFreq driver which works with
> existing CPUFreq governors. The backend CPPC methods for
> parsing the CPPC table and reading/writing using CPPC semantics
> are abstracted away such that they can be used by any other CPPC
> based CPUFreq driver in the future.
> 
> Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>

I promised to review this one (long ago, sorry about that).

> ---
>  drivers/cpufreq/Kconfig.arm    |  15 +
>  drivers/cpufreq/Makefile       |   1 +
>  drivers/cpufreq/cppc_acpi.c    | 801 +++++++++++++++++++++++++++++++++++++++++
>  drivers/cpufreq/cppc_acpi.h    | 134 +++++++
>  drivers/cpufreq/cppc_cpufreq.c | 186 ++++++++++
>  5 files changed, 1137 insertions(+)
>  create mode 100644 drivers/cpufreq/cppc_acpi.c
>  create mode 100644 drivers/cpufreq/cppc_acpi.h
>  create mode 100644 drivers/cpufreq/cppc_cpufreq.c
> 
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 0f9a2c3..a977d65 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -255,3 +255,18 @@ config ARM_PXA2xx_CPUFREQ
>  	  This add the CPUFreq driver support for Intel PXA2xx SOCs.
>  
>  	  If in doubt, say N.
> +
> +config ACPI_CPPC_CPUFREQ
> +	tristate "CPUFreq driver based on the ACPI CPPC spec"
> +	depends on PCC
> +	help
> +		This adds a CPUFreq driver which uses CPPC methods
> +		as described in the ACPIv5.1 spec. CPPC stands for
> +		Collaborative Processor Performance Controls. It
> +		is based on an abstract continuous scale of CPU
> +		performance values which allows the remote power
> +		processor to flexibly optimize for power and
> +		performance. CPPC relies on power management firmware
> +		for its operation.
> +
> +		If in doubt, say N.
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index b3ca7b0..a7b0b41 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_ARM_SA1110_CPUFREQ)	+= sa1110-cpufreq.o
>  obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
>  obj-$(CONFIG_ARM_TEGRA_CPUFREQ)		+= tegra-cpufreq.o
>  obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
> +obj-$(CONFIG_ACPI_CPPC_CPUFREQ) += cppc_cpufreq.o cppc_acpi.o
>  
>  ##################################################################################
>  # PowerPC platform drivers
> diff --git a/drivers/cpufreq/cppc_acpi.c b/drivers/cpufreq/cppc_acpi.c
> new file mode 100644
> index 0000000..0df80af
> --- /dev/null
> +++ b/drivers/cpufreq/cppc_acpi.c
> @@ -0,0 +1,801 @@
> +/*
> + * CPPC (Collaborative Processor Performance Control) methods used
> + * by CPUfreq drivers.
> + *
> + * (C) Copyright 2014 Linaro Ltd.
> + * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; version 2
> + * of the License.
> + *
> + * CPPC describes a few methods for controlling CPU performance using
> + * information from a per CPU table called CPC. This table is described in
> + * the ACPI v5.0+ specification. The table consists of a list of
> + * registers which may be memory mapped or hardware registers and also may
> + * include some static integer values.
> + *
> + * CPU performance is on an abstract continuous scale as against a discretized
> + * P-state scale which is tied to CPU frequency only. In brief, the basic
> + * operation involves:
> + *
> + * - OS makes a CPU performance request. (Can provide min and max bounds)
> + *
> + * - Platform (such as BMC) is free to optimize request within requested bounds
> + *   depending on power/thermal budgets etc.
> + *
> + * - Platform conveys its decision back to OS
> + *
> + * The communication between OS and platform occurs through another medium
> + * called (PCC) Platform Communication Channel. This is a generic mailbox like
> + * mechanism which includes doorbell semantics to indicate register updates.
> + * See drivers/mailbox/pcc.c for details on PCC.
> + *
> + * Finer details about the PCC and CPPC spec are available in the latest
> + * ACPI 5.1 specification.
> + */
> +
> +#include <linux/cpufreq.h>
> +#include <linux/delay.h>
> +
> +#include "cppc_acpi.h"
> +/*
> + * Lock to provide mutually exclusive access to the PCC
> + * channel. e.g. When the remote updates the shared region
> + * with new data, the reader needs to be protected from
> + * other CPUs activity on the same channel.
> + */
> +static DEFINE_SPINLOCK(pcc_lock);
> +
> +static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
> +
> +/* This layer handles all the PCC specifics for CPPC. */
> +static struct mbox_chan *pcc_channel;
> +static void __iomem *pcc_comm_addr;
> +static u64 comm_base_addr;
> +static int pcc_subspace_idx = -1;
> +static u16 pcc_cmd_delay;
> +
> +static int send_pcc_cmd(u16 cmd)
> +{
> +	int err;
> +	struct acpi_pcct_hw_reduced *pcct_ss = pcc_channel->con_priv;
> +	struct acpi_pcct_shared_memory *generic_comm_base =
> +		(struct acpi_pcct_shared_memory *) pcc_comm_addr;
> +	u32 cmd_latency = pcct_ss->latency;
> +
> +	/* Write to the shared comm region. */
> +	writew(cmd, &generic_comm_base->command);
> +
> +	/* Flip CMD COMPLETE bit */
> +	writew(0, &generic_comm_base->status);
> +
> +	err = mbox_send_message(pcc_channel, &cmd);
> +	if (err < 0) {
> +		pr_err("Err sending PCC mbox message. cmd = %d, ret = %d\n",
> +				cmd, err);
> +		return err;
> +	}
> +
> +	/* Wait till platform processes command. */
> +	udelay(cmd_latency);
> +
> +	if (!(readw_relaxed(&generic_comm_base->status)
> +		    & PCC_CMD_COMPLETE))
> +		mbox_client_txdone(pcc_channel, -EIO);
> +	else
> +		/* Success */
> +		mbox_client_txdone(pcc_channel, 0);

What about doing

	int result;

	result = readw_relaxed(&generic_comm_base->status) & PCC_CMD_COMPLETE ? 0 : -EIO;
	mbox_client_txdone(pcc_channel, result);

> +
> +	return 0;

Why do we want to return 0 even if 'result' is not 0?

> +}
> +
> +static void cppc_chan_tx_done(struct mbox_client *cl, void *mssg, int ret)
> +{
> +	if (!ret)
> +		pr_debug("CPPC TX completed. CMD sent = %x, ret = %d\n",
> +				*(u16 *)mssg, ret);
> +	else
> +		pr_warn("CPPC TX did not complete: CMD sent = %x, ret = %d\n",
> +				*(u16 *)mssg, ret);

Should that be pr_debug() too?  Also I'd prefer the

	if (ret) ... else ...

ordering as it avoids the extra logical negation.

> +}
> +
> +struct mbox_client cppc_mbox_cl = {
> +	.tx_done = cppc_chan_tx_done,
> +	.knows_txdone = true,
> +};
> +
> +/* XXX: Temp adaptation from processor_perflib.c
> + * until we get ACPI CPU idle support on ARM64.
> + */
> +
> +static int acpi_get_psd(struct cpudata *pr)
> +{
> +	int result = 0;
> +	acpi_status status = AE_OK;
> +	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
> +	struct acpi_buffer format = {sizeof("NNNNN"), "NNNNN"};
> +	struct acpi_buffer state = {0, NULL};
> +	union acpi_object  *psd = NULL;
> +	struct acpi_psd_package *pdomain;
> +	acpi_handle handle;
> +	char proc_name[11];
> +
> +	sprintf(proc_name, "\\_PR.CPU%d", pr->cpu);
> +
> +	status = acpi_get_handle(NULL, proc_name, &handle);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	status = acpi_evaluate_object(handle, "_PSD", NULL, &buffer);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	psd = buffer.pointer;
> +	if (!psd || (psd->type != ACPI_TYPE_PACKAGE)) {
> +		pr_err("Invalid _PSD data\n");

_debug(), please?  And what about using acpi_handle_debug() for that matter?

> +		result = -EFAULT;

-ENODATA would be better.

> +		goto end;
> +	}
> +
> +	if (psd->package.count != 1) {
> +		pr_err("Invalid _PSD data\n");
> +		result = -EFAULT;

Likewise.  And below too.

> +		goto end;
> +	}
> +
> +	pdomain = &(pr->domain_info);
> +
> +	state.length = sizeof(struct acpi_psd_package);
> +	state.pointer = pdomain;
> +
> +	status = acpi_extract_package(&(psd->package.elements[0]),
> +		&format, &state);
> +	if (ACPI_FAILURE(status)) {
> +		pr_err("Invalid _PSD data\n");
> +		result = -EFAULT;
> +		goto end;
> +	}
> +
> +	if (pdomain->num_entries != ACPI_PSD_REV0_ENTRIES) {
> +		pr_err("Unknown _PSD:num_entries\n");
> +		result = -EFAULT;
> +		goto end;
> +	}
> +
> +	if (pdomain->revision != ACPI_PSD_REV0_REVISION) {
> +		pr_err("Unknown _PSD:revision\n");
> +		result = -EFAULT;
> +		goto end;
> +	}
> +
> +	if (pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ALL &&
> +	    pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ANY &&
> +	    pdomain->coord_type != DOMAIN_COORD_TYPE_HW_ALL) {
> +		pr_err("Invalid _PSD:coord_type\n");
> +		result = -EFAULT;
> +		goto end;
> +	}
> +end:
> +	kfree(buffer.pointer);
> +	return result;
> +}
> +
> +/* XXX: Temp adaptation from processor_perflib.c
> + * until we get ACPI CPU idle support on ARM64.
> + */
> +int acpi_get_psd_map(struct cpudata **all_cpu_data)
> +{
> +	int count_target;
> +	int retval = 0;
> +	unsigned int i, j;
> +	cpumask_var_t covered_cpus;
> +	struct cpudata *pr;
> +	struct acpi_psd_package *pdomain;
> +	struct cpudata *match_pr;
> +	struct acpi_psd_package *match_pdomain;
> +
> +	if (!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))
> +		return -ENOMEM;
> +
> +	/* Call _PSD for all CPUs */
> +	for_each_online_cpu(i) {

Why do we do that for online CPUs only?

> +		pr = all_cpu_data[i];
> +		if (!pr)
> +			continue;
> +
> +		if (!zalloc_cpumask_var_node(&pr->shared_cpu_map,
> +					GFP_KERNEL, cpu_to_node(pr->cpu))) {
> +			pr_err("No mem for shared_cpus cpumask\n");

Again, this doesn't need to be an error-level kernel message.  And please say
"memory" instead of "mem".

> +			return -ENOMEM;
> +		}
> +
> +		cpumask_set_cpu(i, pr->shared_cpu_map);
> +		if (acpi_get_psd(pr)) {
> +			retval = -EINVAL;
> +			continue;
> +		}
> +	}
> +	if (retval)
> +		goto err_ret;
> +
> +	/*
> +	 * Now that we have _PSD data from all CPUs, lets setup P-state
> +	 * domain info.
> +	 */
> +	for_each_online_cpu(i) {
> +		pr = all_cpu_data[i];
> +		if (!pr)
> +			continue;
> +
> +		if (cpumask_test_cpu(i, covered_cpus))
> +			continue;
> +
> +		pdomain = &(pr->domain_info);
> +		cpumask_set_cpu(i, pr->shared_cpu_map);
> +		cpumask_set_cpu(i, covered_cpus);
> +		if (pdomain->num_processors <= 1)
> +			continue;
> +
> +		/* Validate the Domain info */
> +		count_target = pdomain->num_processors;
> +		if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
> +			pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
> +		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
> +			pr->shared_type = CPUFREQ_SHARED_TYPE_HW;
> +		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
> +			pr->shared_type = CPUFREQ_SHARED_TYPE_ANY;
> +
> +		for_each_online_cpu(j) {
> +			if (i == j)
> +				continue;
> +
> +			match_pr = all_cpu_data[j];
> +			if (!match_pr)
> +				continue;
> +
> +			match_pdomain = &(match_pr->domain_info);
> +			if (match_pdomain->domain != pdomain->domain)
> +				continue;
> +
> +			/* Here i and j are in the same domain */
> +
> +			if (match_pdomain->num_processors != count_target) {
> +				retval = -EINVAL;
> +				goto err_ret;
> +			}
> +
> +			if (pdomain->coord_type != match_pdomain->coord_type) {
> +				retval = -EINVAL;
> +				goto err_ret;
> +			}
> +
> +			cpumask_set_cpu(j, covered_cpus);
> +			cpumask_set_cpu(j, pr->shared_cpu_map);
> +		}
> +
> +		for_each_online_cpu(j) {
> +			if (i == j)
> +				continue;
> +
> +			match_pr = all_cpu_data[j];
> +			if (!match_pr)
> +				continue;
> +
> +			match_pdomain = &(match_pr->domain_info);
> +			if (match_pdomain->domain != pdomain->domain)
> +				continue;
> +
> +			match_pr->shared_type =
> +					pr->shared_type;


Line break not needed here.

> +			cpumask_copy(match_pr->shared_cpu_map,
> +				     pr->shared_cpu_map);
> +		}
> +	}
> +
> +err_ret:
> +	for_each_online_cpu(i) {
> +		pr = all_cpu_data[i];
> +		if (!pr)
> +			continue;
> +
> +		/* Assume no coordination on any error parsing domain info */
> +		if (retval) {
> +			cpumask_clear(pr->shared_cpu_map);
> +			cpumask_set_cpu(i, pr->shared_cpu_map);
> +			pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
> +		}
> +	}
> +
> +	free_cpumask_var(covered_cpus);
> +	return retval;
> +}
> +EXPORT_SYMBOL(acpi_get_psd_map);
> +
> +/**
> + * acpi_cppc_processor_probe -

No line break here, please and this should be a single line.

> + * The _CPC table is a per CPU table which a bunch of entries which
> + * may be registers or integers.
> + * An example table looks like the following.
> + *
> + *	Name(_CPC, Package()
> + *			{
> + *			17,
> + *			NumEntries
> + *			1,
> + *			// Revision
> + *			ResourceTemplate(){Register(PCC, 32, 0, 0x120, 2)},
> + *			// Highest Performance
> + *			ResourceTemplate(){Register(PCC, 32, 0, 0x124, 2)},
> + *			// Nominal Performance
> + *			ResourceTemplate(){Register(PCC, 32, 0, 0x128, 2)},
> + *			// Lowest Nonlinear Performance
> + *			ResourceTemplate(){Register(PCC, 32, 0, 0x12C, 2)},
> + *			// Lowest Performance
> + *			ResourceTemplate(){Register(PCC, 32, 0, 0x130, 2)},
> + *			// Guaranteed Performance Register
> + *			ResourceTemplate(){Register(PCC, 32, 0, 0x110, 2)},
> + *			// Desired Performance Register
> + *			ResourceTemplate(){Register(SystemMemory, 0, 0, 0, 0)},
> + *			..
> + *			..
> + *			..
> + *
> + *		}
> + * Each Register() encodes how to access that specific register.
> + * e.g. a sample PCC entry has the following encoding:
> + *
> + *	Register (
> + *		PCC,
> + *		AddressSpaceKeyword
> + *		8,
> + *		//RegisterBitWidth
> + *		8,
> + *		//RegisterBitOffset
> + *		0x30,
> + *		//RegisterAddress
> + *		9
> + *		//AccessSize (subspace ID)
> + *		0
> + *		)
> + *		}
> + *
> + *	This function walks through all the per CPU _CPC entries and extracts
> + *	the Register details.
> + *
> + *	Return: 0 for success or negative value for err.
> + */
> +int acpi_cppc_processor_probe(void)
> +{
> +	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
> +	union acpi_object *out_obj, *cpc_obj;
> +	struct cpc_desc *current_cpu_cpc;
> +	struct cpc_reg *gas_t;
> +	struct acpi_pcct_subspace *cppc_ss;
> +	char proc_name[11];
> +	unsigned int num_ent, ret = 0, i, cpu, len;
> +	acpi_handle handle;
> +	acpi_status status;
> +
> +	/* Parse the ACPI _CPC table for each cpu. */
> +	for_each_online_cpu(cpu) {
> +		sprintf(proc_name, "\\_PR.CPU%d", cpu);
> +
> +		status = acpi_get_handle(NULL, proc_name, &handle);
> +		if (ACPI_FAILURE(status)) {
> +			ret = -ENODEV;
> +			goto out_free;
> +		}
> +
> +		if (!acpi_has_method(handle, "_CPC")) {
> +			ret = -ENODEV;
> +			goto out_free;
> +		}
> +
> +		status = acpi_evaluate_object(handle, "_CPC", NULL, &output);
> +		if (ACPI_FAILURE(status)) {
> +			ret = -ENODEV;
> +			goto out_free;
> +		}
> +
> +		out_obj = (union acpi_object *) output.pointer;
> +		if (out_obj->type != ACPI_TYPE_PACKAGE) {
> +			ret = -ENODEV;
> +			goto out_free;
> +		}
> +
> +		current_cpu_cpc = kzalloc(sizeof(struct cpc_desc), GFP_KERNEL);
> +		if (!current_cpu_cpc)
> +			return -ENOMEM;
> +
> +		num_ent = out_obj->package.count;
> +
> +		pr_debug("num_ent in CPC table:%d\n", num_ent);
> +
> +		/* Iterate through each entry in _CPC */
> +		for (i = 2; i < num_ent; i++) {
> +			cpc_obj = &out_obj->package.elements[i];
> +
> +			if (cpc_obj->type == ACPI_TYPE_INTEGER)	{
> +				current_cpu_cpc->cpc_regs[i-2].type =
> +					ACPI_TYPE_INTEGER;
> +				current_cpu_cpc->cpc_regs[i-2].cpc_entry.int_value =
> +					cpc_obj->integer.value;
> +			} else if (cpc_obj->type == ACPI_TYPE_BUFFER) {
> +				gas_t = (struct cpc_reg *)
> +					cpc_obj->buffer.pointer;
> +
> +				/*
> +				 * The PCC Subspace index is encoded inside
> +				 * the CPC table entries. The same PCC index
> +				 * will be used for all the PCC entries,
> +				 * so extract it only once.
> +				 */
> +				if (gas_t->space_id ==
> +						ACPI_ADR_SPACE_PLATFORM_COMM) {
> +					if (pcc_subspace_idx < 0)
> +						pcc_subspace_idx =
> +							gas_t->access_width;
> +				}
> +
> +				/*
> +				 * First two entires are Version and num of
> +				 * entries. Rest of them are registers or
> +				 * ints. Hence the loop begins at 2.
> +				 * Get each reg info.
> +				 */
> +				current_cpu_cpc->cpc_regs[i-2].type =
> +					ACPI_TYPE_BUFFER;
> +				current_cpu_cpc->cpc_regs[i-2].cpc_entry.reg =
> +					(struct cpc_reg) {
> +						.space_id = gas_t->space_id,
> +						.length	= gas_t->length,
> +						.bit_width = gas_t->bit_width,
> +						.bit_offset = gas_t->bit_offset,
> +						.address = gas_t->address,
> +						.access_width =
> +							gas_t->access_width,
> +					};
> +			} else {
> +				pr_err("Error in entry:%d in CPC table.\n", i);

Again, lower message lever.

> +				ret = -EINVAL;

-EINVAL means "invalid argument".  Is this what you want here?

> +				goto out_free;
> +			}
> +		}
> +
> +		/* Plug it into this CPUs CPC descriptor. */
> +		per_cpu(cpc_desc_ptr, cpu) = current_cpu_cpc;
> +	}
> +
> +	/*
> +	 * Now that we have all the information from the CPC table,
> +	 * lets get a mailbox channel from the mailbox controller.
> +	 * The channel for client is indexed using the subspace id
> +	 * which was encoded in the Register(PCC.. entries.
> +	 */
> +	pr_debug("Completed parsing, now onto PCC init\n");
> +
> +	if (pcc_subspace_idx >= 0) {
> +		pcc_channel = pcc_mbox_request_channel(&cppc_mbox_cl,
> +				pcc_subspace_idx);
> +
> +		if (IS_ERR(pcc_channel)) {
> +			pr_err("No PCC communication channel found\n");
> +			ret = -ENODEV;
> +			goto out_free;
> +		}
> +
> +
> +		/*
> +		 * The PCC mailbox controller driver should
> +		 * have parsed the PCCT (global table of all
> +		 * PCC channels) and stored pointers to the
> +		 * subspace communication region in con_priv.
> +		 */
> +		cppc_ss = pcc_channel->con_priv;
> +
> +		if (!cppc_ss) {
> +			pr_err("No PCC subspace found for CPPC\n");
> +			ret = -ENODEV;
> +			goto out_free;
> +		}
> +
> +		/*
> +		 * This is the shared communication region
> +		 * for the OS and Platform to communicate over.
> +		 */
> +		comm_base_addr = cppc_ss->base_address;
> +		len = cppc_ss->length;
> +		pcc_cmd_delay = cppc_ss->min_turnaround_time;
> +
> +		pr_debug("From PCCT: CPPC subspace addr:%llx, len: %d\n",
> +				comm_base_addr, len);
> +		pcc_comm_addr = ioremap(comm_base_addr, len);
> +		if (!pcc_comm_addr) {
> +			ret = -ENOMEM;
> +			pr_err("Failed to ioremap PCC comm region mem\n");
> +			goto out_free;
> +		}
> +
> +		pr_debug("New PCC comm space addr: %llx\n", (u64)pcc_comm_addr);
> +
> +	} else
> +		/* For the case where registers are not defined as PCC regs. */
> +		pr_warn("No PCC subspace detected in any CPC entries.\n");
> +
> +	/* Everything looks okay */
> +	pr_info("Successfully parsed all CPC structs\n");
> +
> +	kfree(output.pointer);
> +	return 0;
> +
> +out_free:
> +	for_each_online_cpu(cpu) {
> +		current_cpu_cpc = per_cpu(cpc_desc_ptr, cpu);
> +		kfree(current_cpu_cpc);
> +	}
> +
> +	kfree(output.pointer);
> +	return -ENODEV;
> +}
> +EXPORT_SYMBOL(acpi_cppc_processor_probe);
> +
> +static u64 cpc_trans(struct cpc_register_resource *reg, int cmd, u64 write_val,
> +		bool is_pcc)
> +{
> +	u64 addr;
> +	u64 read_val = 0;
> +
> +	/* PCC communication addr space begins at byte offset 0x8. */
> +	if (is_pcc == true)

Ugh.

> +		addr = (u64)pcc_comm_addr + 0x8 + reg->cpc_entry.reg.address;
> +	else
> +		addr = reg->cpc_entry.reg.address;


What about

	addr = is_pcc ? (u64)pcc_comm_addr + 0x8 + reg->cpc_entry.reg.address :
			reg->cpc_entry.reg.address;

> +
> +	if (reg->type == ACPI_TYPE_BUFFER) {
> +		switch (reg->cpc_entry.reg.bit_width) {
> +		case 8:
> +			if (cmd == CMD_READ)
> +				read_val = readb((void *) (addr));
> +			else if (cmd == CMD_WRITE)
> +				writeb(write_val, (void *)(addr));
> +			else
> +				pr_err("Unsupported cmd type: %d\n", cmd);

Please reduce the log level of *all* debug messages in this patch.  Also please
add information allowing whoever reads those messages to identify the affected
device in the first place to all of them.

> +			break;
> +		case 16:
> +			if (cmd == CMD_READ)
> +				read_val = readw((void *) (addr));
> +			else if (cmd == CMD_WRITE)
> +				writew(write_val, (void *)(addr));
> +			else
> +				pr_err("Unsupported cmd type: %d\n", cmd);
> +			break;
> +		case 32:
> +			if (cmd == CMD_READ)
> +				read_val = readl((void *) (addr));
> +			else if (cmd == CMD_WRITE)
> +				writel(write_val, (void *)(addr));
> +			else
> +				pr_err("Unsupported cmd type: %d\n", cmd);
> +			break;
> +		case 64:
> +			if (cmd == CMD_READ)
> +				read_val = readq((void *) (addr));
> +			else if (cmd == CMD_WRITE)
> +				writeq(write_val, (void *)(addr));
> +			else
> +				pr_err("Unsupported cmd type: %d\n", cmd);
> +			break;
> +		default:
> +			pr_err("Unsupported bit width for CPC read/write (cmd:%d)\n",
> +					cmd);
> +			break;
> +		}
> +	} else if (reg->type == ACPI_TYPE_INTEGER) {
> +		if (cmd == CMD_READ)
> +			read_val = reg->cpc_entry.int_value;
> +		else if (cmd == CMD_WRITE)
> +			reg->cpc_entry.int_value = write_val;
> +		else
> +			pr_err("Unsupported cmd type: %d\n", cmd);
> +	} else
> +		pr_err("Unsupported CPC entry type :%d\n", reg->type);
> +
> +	return read_val;
> +}
> +
> +/**
> + * cppc_get_perf_caps - Get a CPUs performance capabilities.
> + * @cpunum: CPU from which to get capabilities info.
> + * @perf_caps: ptr to cppc_perf_caps. See cppc_acpi.h
> + *
> + * Return - 0 for success with perf_caps populated else
> + *	-ERRNO.
> + */
> +int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
> +{
> +	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
> +	struct cpc_register_resource *highest_reg, *lowest_reg, *ref_perf,
> +				     *nom_perf;
> +	u64 min, max, ref, nom;
> +	bool is_pcc = false;
> +
> +	if (!cpc_desc) {
> +		pr_err("No CPC descriptor for CPU:%d\n", cpunum);
> +		return -ENODEV;
> +	}
> +
> +	highest_reg = &cpc_desc->cpc_regs[HIGHEST_PERF];
> +	lowest_reg = &cpc_desc->cpc_regs[LOWEST_PERF];
> +	ref_perf = &cpc_desc->cpc_regs[REFERENCE_PERF];
> +	nom_perf = &cpc_desc->cpc_regs[NOMINAL_PERF];
> +
> +	spin_lock(&pcc_lock);

Don't you need to disable interrupts here?

> +
> +	/* Are any of the regs PCC ?*/
> +	if ((highest_reg->cpc_entry.reg.space_id ==
> +				ACPI_ADR_SPACE_PLATFORM_COMM) ||
> +			(lowest_reg->cpc_entry.reg.space_id ==
> +			 ACPI_ADR_SPACE_PLATFORM_COMM) ||
> +			(ref_perf->cpc_entry.reg.space_id ==
> +			 ACPI_ADR_SPACE_PLATFORM_COMM) ||
> +			(nom_perf->cpc_entry.reg.space_id ==
> +			 ACPI_ADR_SPACE_PLATFORM_COMM))
> +		is_pcc = true;
> +
> +	if (is_pcc == true) {

Again.  Please do

	if (is_pcc) {

> +		/*
> +		 * Min time OS should wait before sending
> +		 * next command.
> +		 */
> +		udelay(pcc_cmd_delay);
> +		/* Ring doorbell */
> +		send_pcc_cmd(CMD_READ);
> +	}
> +
> +	max = cpc_trans(highest_reg, CMD_READ, 0, is_pcc);
> +	perf_caps->highest_perf = max;
> +
> +	min = cpc_trans(lowest_reg, CMD_READ, 0, is_pcc);
> +	perf_caps->lowest_perf = min;
> +
> +	ref = cpc_trans(ref_perf, CMD_READ, 0, is_pcc);
> +	perf_caps->reference_perf = ref;
> +
> +	pr_err("Ref perf: %d\n", perf_caps->reference_perf);
> +
> +	nom = cpc_trans(nom_perf, CMD_READ, 0, is_pcc);
> +	perf_caps->nominal_perf = nom;
> +
> +	pr_err("Nom perf: %d\n", perf_caps->nominal_perf);
> +
> +	if (!ref)
> +		perf_caps->reference_perf = perf_caps->nominal_perf;
> +
> +	spin_unlock(&pcc_lock);
> +
> +	if (!perf_caps->highest_perf ||
> +			!perf_caps->lowest_perf ||
> +			!perf_caps->reference_perf ||
> +			!perf_caps->nominal_perf) {
> +		pr_err("Err reading CPU performance limits\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(cppc_get_perf_caps);

EXPORT_SYMBOL_GPL(), please.

Here and elsewhere.

> +
> +/**
> + * cppc_get_perf_ctrs - Read a CPUs performance feedback counters.
> + * @cpunum: CPU from which to read counters.
> + * @perf_fb_ctrs: ptr to cppc_perf_fb_ctrs. See cppc_acpi.h
> + *
> + * Return - 0 for success with perf_fb_ctrs populated else
> + *	-ERRNO.
> + */
> +int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
> +{
> +	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
> +	struct cpc_register_resource *delivered_reg, *reference_reg;
> +	u64 delivered, reference;
> +	bool is_pcc = false;
> +
> +	if (!cpc_desc) {
> +		pr_err("No CPC descriptor for CPU:%d\n", cpunum);
> +		return -ENODEV;
> +	}
> +
> +	delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];
> +	reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];
> +
> +	spin_lock(&pcc_lock);
> +
> +	/* Are any of the regs PCC ?*/
> +	if ((delivered_reg->cpc_entry.reg.space_id ==
> +				ACPI_ADR_SPACE_PLATFORM_COMM) ||
> +			(reference_reg->cpc_entry.reg.space_id ==
> +			 ACPI_ADR_SPACE_PLATFORM_COMM))
> +		is_pcc = true;
> +
> +	if (is_pcc == true) {
> +		/*
> +		 * Min time OS should wait before sending
> +		 * next command.
> +		 */
> +		udelay(pcc_cmd_delay);
> +		/* Ring doorbell */
> +		send_pcc_cmd(CMD_READ);
> +	}
> +
> +	delivered = cpc_trans(delivered_reg, CMD_READ, 0, is_pcc);
> +	reference = cpc_trans(reference_reg, CMD_READ, 0, is_pcc);
> +
> +	spin_unlock(&pcc_lock);
> +
> +	if (!delivered || !reference) {
> +		pr_err("Bogus values from Delivered or Reference counters\n");
> +		return -EINVAL;
> +	}
> +
> +	perf_fb_ctrs->delivered = delivered;
> +	perf_fb_ctrs->reference = reference;
> +
> +	perf_fb_ctrs->delivered -= perf_fb_ctrs->prev_delivered;
> +	perf_fb_ctrs->reference -= perf_fb_ctrs->prev_reference;
> +
> +	perf_fb_ctrs->prev_delivered = delivered;
> +	perf_fb_ctrs->prev_reference = reference;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(cppc_get_perf_ctrs);
> +
> +/**
> + * cppc_set_perf - Set a CPUs performance controls.
> + * @cpu: CPU for which to set performance controls.
> + * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
> + *
> + * Return: 0 for success, -ERRNO otherwise.
> + */
> +int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
> +{
> +	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
> +	struct cpc_register_resource *desired_reg;
> +	int ret = 0;
> +	bool is_pcc = false;
> +
> +	if (!cpc_desc) {
> +		pr_err("No CPC descriptor for CPU:%d\n", cpu);
> +		return -ENODEV;
> +	}
> +
> +	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
> +
> +	spin_lock(&pcc_lock);
> +
> +	/* Is this a PCC reg ?*/
> +	if (desired_reg->cpc_entry.reg.space_id ==
> +			ACPI_ADR_SPACE_PLATFORM_COMM)
> +		is_pcc = true;
> +
> +	cpc_trans(desired_reg, CMD_WRITE,
> +			perf_ctrls->desired_perf, is_pcc);
> +
> +	if (is_pcc == true) {
> +		/*
> +		 * Min time OS should wait before sending
> +		 * next command.
> +		 */
> +		udelay(pcc_cmd_delay);
> +		/* Ring doorbell */
> +		send_pcc_cmd(CMD_READ);
> +	}
> +
> +	spin_unlock(&pcc_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(cppc_set_perf);
> +
> diff --git a/drivers/cpufreq/cppc_acpi.h b/drivers/cpufreq/cppc_acpi.h
> new file mode 100644
> index 0000000..a6c7ff6
> --- /dev/null
> +++ b/drivers/cpufreq/cppc_acpi.h
> @@ -0,0 +1,134 @@
> +/*
> + * CPPC (Collaborative Processor Performance Control) methods used
> + * by CPUfreq drivers.
> + *
> + * (C) Copyright 2014 Linaro Ltd.
> + * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; version 2
> + * of the License.
> + */
> +
> +#ifndef _CPPC_ACPI_H
> +#define _CPPC_ACPI_H
> +
> +#include <linux/acpi.h>
> +#include <linux/mailbox_controller.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/types.h>
> +
> +#include <acpi/processor.h>
> +
> +#define PCC_CMD_COMPLETE 1
> +#define MAX_CPC_REG_ENT 19
> +
> +/* CPPC specific PCC commands. */
> +#define	CMD_READ 0
> +#define	CMD_WRITE 1
> +
> +/* Each register has the folowing format. */
> +struct cpc_reg {
> +	u8 descriptor;
> +	u16 length;
> +	u8 space_id;
> +	u8 bit_width;
> +	u8 bit_offset;
> +	u8 access_width;
> +	u64 __iomem address;
> +} __packed;
> +
> +/*
> + * Each entry in the CPC table is either
> + * of type ACPI_TYPE_BUFFER or
> + * ACPI_TYPE_INTEGER.
> + */
> +struct cpc_register_resource {
> +	acpi_object_type type;
> +	union {
> +		struct cpc_reg reg;
> +		u64 int_value;
> +	} cpc_entry;
> +};
> +
> +/* Container to hold the CPC details for each CPU */
> +struct cpc_desc {
> +	int num_entries;
> +	int version;
> +	struct cpc_register_resource cpc_regs[MAX_CPC_REG_ENT];
> +};
> +
> +/* These are indexes into the per-cpu cpc_regs[]. Order is important. */
> +enum cppc_regs {
> +	HIGHEST_PERF,
> +	NOMINAL_PERF,
> +	LOW_NON_LINEAR_PERF,
> +	LOWEST_PERF,
> +	GUARANTEED_PERF,
> +	DESIRED_PERF,
> +	MIN_PERF,
> +	MAX_PERF,
> +	PERF_REDUC_TOLERANCE,
> +	TIME_WINDOW,
> +	CTR_WRAP_TIME,
> +	REFERENCE_CTR,
> +	DELIVERED_CTR,
> +	PERF_LIMITED,
> +	ENABLE,
> +	AUTO_SEL_ENABLE,
> +	AUTO_ACT_WINDOW,
> +	ENERGY_PERF,
> +	REFERENCE_PERF,
> +};
> +
> +/*
> + * Categorization of registers as described
> + * in the ACPI v.5.1 spec.
> + * XXX: Only filling up ones which are used by governors
> + * today.
> + */
> +struct cppc_perf_caps {
> +	u32 highest_perf;
> +	u32 nominal_perf;
> +	u32 reference_perf;
> +	u32 lowest_perf;
> +};
> +
> +struct cppc_perf_ctrls {
> +	u32 max_perf;
> +	u32 min_perf;
> +	u32 desired_perf;
> +};
> +
> +struct cppc_perf_fb_ctrs {
> +	u64 reference;
> +	u64 prev_reference;
> +	u64 delivered;
> +	u64 prev_delivered;
> +};
> +
> +/* Per CPU container for runtime CPPC management. */
> +struct cpudata {
> +	int cpu;
> +	struct cppc_perf_caps perf_caps;
> +	struct cppc_perf_ctrls perf_ctrls;
> +	struct cppc_perf_fb_ctrs perf_fb_ctrs;
> +	struct cpufreq_policy *cur_policy;
> +	struct acpi_psd_package domain_info;
> +	unsigned int shared_type;
> +	cpumask_var_t shared_cpu_map;
> +};
> +

Shouldn't the above definitions go into ACPICA?

> +extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
> +extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
> +extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps);
> +extern int acpi_get_psd_map(struct cpudata **);
> +extern int acpi_cppc_processor_probe(void);
> +
> +/* Methods to interact with the PCC mailbox controller. */
> +extern struct mbox_chan *
> +	pcc_mbox_request_channel(struct mbox_client *, unsigned int);
> +extern int mbox_send_message(struct mbox_chan *chan, void *mssg);
> +
> +#endif /* _CPPC_ACPI_H*/
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> new file mode 100644
> index 0000000..258e27f1
> --- /dev/null
> +++ b/drivers/cpufreq/cppc_cpufreq.c
> @@ -0,0 +1,186 @@
> +/*
> + * CPPC (Collaborative Processor Performance Control) driver for
> + * interfacing with the CPUfreq layer and governors. See
> + * cppc_acpi.c for CPPC specific methods.
> + *
> + * (C) Copyright 2014 Linaro Ltd.
> + * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; version 2
> + * of the License.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/delay.h>
> +#include <linux/cpu.h>
> +#include <linux/cpufreq.h>
> +#include <linux/vmalloc.h>
> +
> +#include "cppc_acpi.h"
> +
> +static struct cpudata **all_cpu_data;
> +
> +static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
> +		unsigned int target_freq,
> +		unsigned int relation)
> +{
> +	struct cpudata *cpu;
> +	struct cpufreq_freqs freqs;
> +	int ret;
> +
> +	cpu = all_cpu_data[policy->cpu];
> +
> +	cpu->perf_ctrls.desired_perf = target_freq;
> +	freqs.old = policy->cur;
> +	freqs.new = target_freq;
> +
> +	cpufreq_freq_transition_begin(policy, &freqs);
> +	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
> +	cpufreq_freq_transition_end(policy, &freqs, ret != 0);
> +
> +	if (ret) {
> +		pr_debug("Failed to set target on CPU:%d\n", cpu->cpu);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static unsigned int cppc_cpufreq_get_perf(unsigned int cpu_num)
> +{
> +	struct cpudata *cpu;
> +	int32_t delivered_perf = 1;
> +
> +	cpu = all_cpu_data[cpu_num];
> +	if (!cpu)
> +		return 0;
> +
> +	cppc_get_perf_ctrs(cpu_num, &cpu->perf_fb_ctrs);
> +
> +	delivered_perf = cpu->perf_caps.reference_perf *
> +		cpu->perf_fb_ctrs.delivered;
> +	delivered_perf /= cpu->perf_fb_ctrs.reference;
> +	pr_debug("delivered_perf: %d\n", delivered_perf);
> +	pr_debug("reference_perf: %d\n",
> +			cpu->perf_caps.reference_perf);
> +	pr_debug("delivered, reference deltas: %lld, %lld\n",
> +			cpu->perf_fb_ctrs.delivered,
> +			cpu->perf_fb_ctrs.reference);
> +
> +	return delivered_perf;
> +}
> +
> +static int cppc_verify_policy(struct cpufreq_policy *policy)
> +{
> +	cpufreq_verify_within_cpu_limits(policy);
> +	return 0;
> +}
> +
> +static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
> +{
> +	int cpu_num = policy->cpu;
> +	struct cpudata *cpu = all_cpu_data[cpu_num];
> +	int ret;
> +
> +	pr_info("CPPC ondemand CPU %d exiting\n", cpu_num);
> +
> +	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
> +
> +	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
> +	if (ret)
> +		pr_err("Err setting perf value:%d on CPU:%d\n",
> +				cpu->perf_caps.lowest_perf, cpu_num);
> +}
> +
> +static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
> +{
> +	struct cpudata *cpu;
> +	int ret;
> +
> +	cpu = all_cpu_data[policy->cpu];
> +
> +	cpu->cpu = policy->cpu;
> +	ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
> +
> +	if (ret) {
> +		pr_err("Err reading CPU%d, perf capabilities\n", cpu->cpu);
> +		return -ENODEV;
> +	}
> +
> +	policy->min = cpu->perf_caps.lowest_perf;
> +	policy->max = cpu->perf_caps.highest_perf;
> +	/* cpuinfo and default policy values */
> +	policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf;
> +	policy->cpuinfo.max_freq = cpu->perf_caps.highest_perf;
> +
> +	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL ||
> +	    policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
> +		cpumask_copy(policy->cpus, cpu->shared_cpu_map);
> +
> +	cpumask_set_cpu(policy->cpu, policy->cpus);
> +	cpu->cur_policy = policy;
> +
> +	return 0;
> +}
> +
> +static struct cpufreq_driver cppc_cpufreq_driver = {
> +	.flags = CPUFREQ_CONST_LOOPS,
> +	.verify = cppc_verify_policy,
> +	.target = cppc_cpufreq_set_target,
> +	.get = cppc_cpufreq_get_perf,
> +	.init = cppc_cpufreq_cpu_init,
> +	.stop_cpu = cppc_cpufreq_stop_cpu,
> +	.name = "cppc_cpufreq",
> +};
> +
> +static int __init cppc_cpufreq_init(void)
> +{
> +	int cpu, rc = 0;
> +
> +	if (acpi_disabled)
> +		return -ENODEV;
> +
> +	if (acpi_cppc_processor_probe()) {
> +		pr_err("Err initializing CPC structures\n");
> +		return -ENODEV;
> +	}
> +
> +	pr_info("ACPI CPPC CPUFreq driver initializing.\n");
> +
> +	all_cpu_data = vzalloc(sizeof(void *) * num_possible_cpus());
> +	if (!all_cpu_data)
> +		return -ENOMEM;
> +
> +	for_each_possible_cpu(cpu) {
> +		all_cpu_data[cpu] = kzalloc(sizeof(struct cpudata), GFP_KERNEL);
> +		if (!all_cpu_data[cpu])
> +			return -ENOMEM;
> +	}
> +
> +	rc = acpi_get_psd_map(all_cpu_data);
> +	if (rc) {
> +		pr_err("Err parsing PSD data\n");
> +		goto out;
> +	}
> +
> +	rc = cpufreq_register_driver(&cppc_cpufreq_driver);
> +	if (rc)
> +		goto out;
> +
> +	return rc;
> +
> +out:
> +	get_online_cpus();
> +	for_each_online_cpu(cpu)
> +		if (all_cpu_data[cpu])
> +			kfree(all_cpu_data[cpu]);
> +
> +	put_online_cpus();
> +	vfree(all_cpu_data);
> +	return -ENODEV;
> +}
> +
> +late_initcall(cppc_cpufreq_init);
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH v4 2/2] CPPC: Add CPUFreq driver based on CPPC methods

[Ashwin Chaugule]

Hi Rafael,


On 8 May 2015 at 18:30, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Tuesday, January 27, 2015 04:03:58 PM Ashwin Chaugule wrote:
>> CPPC stands for Collaborative Processor Performance Controls
>> and is defined in the ACPI v5.0+ spec. It describes CPU
>> performance controls on an abstract and continuous scale
>> allowing the platform (e.g. remote power processor) to flexibly
>> optimize CPU performance with its knowledge of power budgets
>> and other architecture specific knowledge.
>>
>> This patch introduces a CPUFreq driver which works with
>> existing CPUFreq governors. The backend CPPC methods for
>> parsing the CPPC table and reading/writing using CPPC semantics
>> are abstracted away such that they can be used by any other CPPC
>> based CPUFreq driver in the future.
>>
>> Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
>
> I promised to review this one (long ago, sorry about that).

Thanks for your time!


>> +
>> +     /* Wait till platform processes command. */
>> +     udelay(cmd_latency);
>> +
>> +     if (!(readw_relaxed(&generic_comm_base->status)
>> +                 & PCC_CMD_COMPLETE))
>> +             mbox_client_txdone(pcc_channel, -EIO);
>> +     else
>> +             /* Success */
>> +             mbox_client_txdone(pcc_channel, 0);
>
> What about doing
>
>         int result;
>
>         result = readw_relaxed(&generic_comm_base->status) & PCC_CMD_COMPLETE ? 0 : -EIO;
>         mbox_client_txdone(pcc_channel, result);

Looks cleaner.

>
>> +
>> +     return 0;
>
> Why do we want to return 0 even if 'result' is not 0?

I'd fixed this locally, by putting a retry loop around the
readw_relaxed() and returning an error if the PCC command doesn't
complete. That would indicate a possible crash on the remote
processor.

>
>> +}
>> +
>> +static void cppc_chan_tx_done(struct mbox_client *cl, void *mssg, int ret)
>> +{
>> +     if (!ret)
>> +             pr_debug("CPPC TX completed. CMD sent = %x, ret = %d\n",
>> +                             *(u16 *)mssg, ret);
>> +     else
>> +             pr_warn("CPPC TX did not complete: CMD sent = %x, ret = %d\n",
>> +                             *(u16 *)mssg, ret);
>
> Should that be pr_debug() too?  Also I'd prefer the
>
>         if (ret) ... else ...
>
> ordering as it avoids the extra logical negation.

Fixed locally.

>> +
>> +/* XXX: Temp adaptation from processor_perflib.c
>> + * until we get ACPI CPU idle support on ARM64.
>> + */
>> +
>> +static int acpi_get_psd(struct cpudata *pr)
>> +{
>> +     int result = 0;
>> +     acpi_status status = AE_OK;
>> +     struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
>> +     struct acpi_buffer format = {sizeof("NNNNN"), "NNNNN"};
>> +     struct acpi_buffer state = {0, NULL};
>> +     union acpi_object  *psd = NULL;
>> +     struct acpi_psd_package *pdomain;
>> +     acpi_handle handle;
>> +     char proc_name[11];
>> +
>> +     sprintf(proc_name, "\\_PR.CPU%d", pr->cpu);
>> +
>> +     status = acpi_get_handle(NULL, proc_name, &handle);
>> +     if (ACPI_FAILURE(status))
>> +             return -ENODEV;
>> +
>> +     status = acpi_evaluate_object(handle, "_PSD", NULL, &buffer);
>> +     if (ACPI_FAILURE(status))
>> +             return -ENODEV;
>> +
>> +     psd = buffer.pointer;
>> +     if (!psd || (psd->type != ACPI_TYPE_PACKAGE)) {
>> +             pr_err("Invalid _PSD data\n");
>
> _debug(), please?  And what about using acpi_handle_debug() for that matter?

>> +             result = -EFAULT;
>
> -ENODATA would be better.
>
>> +             goto end;
>> +     }
>> +
>> +     if (psd->package.count != 1) {
>> +             pr_err("Invalid _PSD data\n");
>> +             result = -EFAULT;
>
> Likewise.  And below too.

Ok. (All this came from processor_perflib.c)

>> +int acpi_get_psd_map(struct cpudata **all_cpu_data)
>> +{
>> +     int count_target;
>> +     int retval = 0;
>> +     unsigned int i, j;
>> +     cpumask_var_t covered_cpus;
>> +     struct cpudata *pr;
>> +     struct acpi_psd_package *pdomain;
>> +     struct cpudata *match_pr;
>> +     struct acpi_psd_package *match_pdomain;
>> +
>> +     if (!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))
>> +             return -ENOMEM;
>> +
>> +     /* Call _PSD for all CPUs */
>> +     for_each_online_cpu(i) {
>
> Why do we do that for online CPUs only?

I've changed this to for_each_possible_cpu(). I was experimenting with
some "partial goods" scenarios. More on that later.

>
>> +             pr = all_cpu_data[i];
>> +             if (!pr)
>> +                     continue;
>> +
>> +             if (!zalloc_cpumask_var_node(&pr->shared_cpu_map,
>> +                                     GFP_KERNEL, cpu_to_node(pr->cpu))) {
>> +                     pr_err("No mem for shared_cpus cpumask\n");
>
> Again, this doesn't need to be an error-level kernel message.  And please say
> "memory" instead of "mem".

Ok. (Came from processor_perflib.c)


>> +
>> +                     match_pr->shared_type =
>> +                                     pr->shared_type;
>
>
> Line break not needed here.

Ok.

>
>> +                     cpumask_copy(match_pr->shared_cpu_map,
>> +                                  pr->shared_cpu_map);
>> +             }
>> +     }
>> +
>> +err_ret:
>> +     for_each_online_cpu(i) {
>> +             pr = all_cpu_data[i];
>> +             if (!pr)
>> +                     continue;
>> +
>> +             /* Assume no coordination on any error parsing domain info */
>> +             if (retval) {
>> +                     cpumask_clear(pr->shared_cpu_map);
>> +                     cpumask_set_cpu(i, pr->shared_cpu_map);
>> +                     pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
>> +             }
>> +     }
>> +
>> +     free_cpumask_var(covered_cpus);
>> +     return retval;
>> +}
>> +EXPORT_SYMBOL(acpi_get_psd_map);
>> +
>> +/**
>> + * acpi_cppc_processor_probe -
>
> No line break here, please and this should be a single line.

Ok.
>

>> +                                     };
>> +                     } else {
>> +                             pr_err("Error in entry:%d in CPC table.\n", i);
>
> Again, lower message lever.
>
>> +                             ret = -EINVAL;
>
> -EINVAL means "invalid argument".  Is this what you want here?

Its an argument from the CPC table. :)
Happy to replace with anything else.


>> +
>> +     /* PCC communication addr space begins at byte offset 0x8. */
>> +     if (is_pcc == true)
>
> Ugh.
>
>> +             addr = (u64)pcc_comm_addr + 0x8 + reg->cpc_entry.reg.address;
>> +     else
>> +             addr = reg->cpc_entry.reg.address;
>
>
> What about
>
>         addr = is_pcc ? (u64)pcc_comm_addr + 0x8 + reg->cpc_entry.reg.address :
>                         reg->cpc_entry.reg.address;
>

Much better. Thanks!


>> +
>> +     if (reg->type == ACPI_TYPE_BUFFER) {
>> +             switch (reg->cpc_entry.reg.bit_width) {
>> +             case 8:
>> +                     if (cmd == CMD_READ)
>> +                             read_val = readb((void *) (addr));
>> +                     else if (cmd == CMD_WRITE)
>> +                             writeb(write_val, (void *)(addr));
>> +                     else
>> +                             pr_err("Unsupported cmd type: %d\n", cmd);
>
> Please reduce the log level of *all* debug messages in this patch.  Also please
> add information allowing whoever reads those messages to identify the affected
> device in the first place to all of them.

Yep. Added a pr_fmt and reduced a lot of prints.


>> + */
>> +int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
>> +{
>> +     struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
>> +     struct cpc_register_resource *highest_reg, *lowest_reg, *ref_perf,
>> +                                  *nom_perf;
>> +     u64 min, max, ref, nom;
>> +     bool is_pcc = false;
>> +
>> +     if (!cpc_desc) {
>> +             pr_err("No CPC descriptor for CPU:%d\n", cpunum);
>> +             return -ENODEV;
>> +     }
>> +
>> +     highest_reg = &cpc_desc->cpc_regs[HIGHEST_PERF];
>> +     lowest_reg = &cpc_desc->cpc_regs[LOWEST_PERF];
>> +     ref_perf = &cpc_desc->cpc_regs[REFERENCE_PERF];
>> +     nom_perf = &cpc_desc->cpc_regs[NOMINAL_PERF];
>> +
>> +     spin_lock(&pcc_lock);
>
> Don't you need to disable interrupts here?

I don't see the case where IRQs could affect this path.

>
>> +
>> +     /* Are any of the regs PCC ?*/
>> +     if ((highest_reg->cpc_entry.reg.space_id ==
>> +                             ACPI_ADR_SPACE_PLATFORM_COMM) ||
>> +                     (lowest_reg->cpc_entry.reg.space_id ==
>> +                      ACPI_ADR_SPACE_PLATFORM_COMM) ||
>> +                     (ref_perf->cpc_entry.reg.space_id ==
>> +                      ACPI_ADR_SPACE_PLATFORM_COMM) ||
>> +                     (nom_perf->cpc_entry.reg.space_id ==
>> +                      ACPI_ADR_SPACE_PLATFORM_COMM))
>> +             is_pcc = true;
>> +
>> +     if (is_pcc == true) {
>
> Again.  Please do
>
>         if (is_pcc) {

Done.


>> +     return 0;
>> +}
>> +EXPORT_SYMBOL(cppc_get_perf_caps);
>
> EXPORT_SYMBOL_GPL(), please.
>
> Here and elsewhere.

Done.


>> diff --git a/drivers/cpufreq/cppc_acpi.h b/drivers/cpufreq/cppc_acpi.h
>> new file mode 100644
>> index 0000000..a6c7ff6
>> --- /dev/null
>> +++ b/drivers/cpufreq/cppc_acpi.h
>> @@ -0,0 +1,134 @@
>> +/*
>> + * CPPC (Collaborative Processor Performance Control) methods used
>> + * by CPUfreq drivers.
>> + *
>> + * (C) Copyright 2014 Linaro Ltd.
>> + * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License
>> + * as published by the Free Software Foundation; version 2
>> + * of the License.
>> + */
>> +
>> +#ifndef _CPPC_ACPI_H
>> +#define _CPPC_ACPI_H
>> +
>> +#include <linux/acpi.h>
>> +#include <linux/mailbox_controller.h>
>> +#include <linux/mailbox_client.h>
>> +#include <linux/types.h>
>> +
>> +#include <acpi/processor.h>
>> +
>> +#define PCC_CMD_COMPLETE 1
>> +#define MAX_CPC_REG_ENT 19
>> +
>> +/* CPPC specific PCC commands. */
>> +#define      CMD_READ 0
>> +#define      CMD_WRITE 1
>> +
>> +/* Each register has the folowing format. */
>> +struct cpc_reg {
>> +     u8 descriptor;
>> +     u16 length;
>> +     u8 space_id;
>> +     u8 bit_width;
>> +     u8 bit_offset;
>> +     u8 access_width;
>> +     u64 __iomem address;
>> +} __packed;
>> +
>> +/*
>> + * Each entry in the CPC table is either
>> + * of type ACPI_TYPE_BUFFER or
>> + * ACPI_TYPE_INTEGER.
>> + */
>> +struct cpc_register_resource {
>> +     acpi_object_type type;
>> +     union {
>> +             struct cpc_reg reg;
>> +             u64 int_value;
>> +     } cpc_entry;
>> +};
>> +
>> +/* Container to hold the CPC details for each CPU */
>> +struct cpc_desc {
>> +     int num_entries;
>> +     int version;
>> +     struct cpc_register_resource cpc_regs[MAX_CPC_REG_ENT];
>> +};
>> +
>> +/* These are indexes into the per-cpu cpc_regs[]. Order is important. */
>> +enum cppc_regs {
>> +     HIGHEST_PERF,
>> +     NOMINAL_PERF,
>> +     LOW_NON_LINEAR_PERF,
>> +     LOWEST_PERF,
>> +     GUARANTEED_PERF,
>> +     DESIRED_PERF,
>> +     MIN_PERF,
>> +     MAX_PERF,
>> +     PERF_REDUC_TOLERANCE,
>> +     TIME_WINDOW,
>> +     CTR_WRAP_TIME,
>> +     REFERENCE_CTR,
>> +     DELIVERED_CTR,
>> +     PERF_LIMITED,
>> +     ENABLE,
>> +     AUTO_SEL_ENABLE,
>> +     AUTO_ACT_WINDOW,
>> +     ENERGY_PERF,
>> +     REFERENCE_PERF,
>> +};
>> +
>> +/*
>> + * Categorization of registers as described
>> + * in the ACPI v.5.1 spec.
>> + * XXX: Only filling up ones which are used by governors
>> + * today.
>> + */
>> +struct cppc_perf_caps {
>> +     u32 highest_perf;
>> +     u32 nominal_perf;
>> +     u32 reference_perf;
>> +     u32 lowest_perf;
>> +};
>> +
>> +struct cppc_perf_ctrls {
>> +     u32 max_perf;
>> +     u32 min_perf;
>> +     u32 desired_perf;
>> +};
>> +
>> +struct cppc_perf_fb_ctrs {
>> +     u64 reference;
>> +     u64 prev_reference;
>> +     u64 delivered;
>> +     u64 prev_delivered;
>> +};
>> +
>> +/* Per CPU container for runtime CPPC management. */
>> +struct cpudata {
>> +     int cpu;
>> +     struct cppc_perf_caps perf_caps;
>> +     struct cppc_perf_ctrls perf_ctrls;
>> +     struct cppc_perf_fb_ctrs perf_fb_ctrs;
>> +     struct cpufreq_policy *cur_policy;
>> +     struct acpi_psd_package domain_info;
>> +     unsigned int shared_type;
>> +     cpumask_var_t shared_cpu_map;
>> +};
>> +
>
> Shouldn't the above definitions go into ACPICA?

I thought about moving this into include/acpi/processor.h along with
all the _PSS etc. stuff. But frankly I'm not sure. For now, I've moved
the cppc_acpi.[c,h] files into drivers/acpi/ and conditionally compile
them via a Kconfig option which is enabled only if
CONFIG_ACPI_PSS(new) is disabled. This is along the lines of what I
wrote in reply to Sudeep's patch[1]. I'd really like to know your
opinions on that approach.

Thanks,
Ashwin.

[1] - http://www.spinics.net/lists/linux-acpi/msg57374.html