[PATCH 04/16] drivers/fsi: Add fsi master definition

[PATCH 04/16] drivers/fsi: Add fsi master definition

[Chris Bostic]

From: Jeremy Kerr <jk@ozlabs.org>

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
---
 drivers/fsi/fsi-core.c   | 20 ++++++++++++++++++++
 drivers/fsi/fsi-master.h | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 drivers/fsi/fsi-master.h

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index 3d55bd5..ce9428d 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -17,6 +17,26 @@
 #include <linux/fsi.h>
 #include <linux/module.h>
 
+#include "fsi-master.h"
+
+static atomic_t master_idx = ATOMIC_INIT(-1);
+
+/* FSI master support */
+
+int fsi_master_register(struct fsi_master *master)
+{
+	master->idx = atomic_inc_return(&master_idx);
+	get_device(master->dev);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fsi_master_register);
+
+void fsi_master_unregister(struct fsi_master *master)
+{
+	put_device(master->dev);
+}
+EXPORT_SYMBOL_GPL(fsi_master_unregister);
+
 /* FSI core & Linux bus type definitions */
 
 static int fsi_bus_match(struct device *dev, struct device_driver *drv)
diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h
new file mode 100644
index 0000000..e75a810
--- /dev/null
+++ b/drivers/fsi/fsi-master.h
@@ -0,0 +1,37 @@
+/*
+ * FSI master definitions. These comprise the core <--> master interface,
+ * to allow the core to interact with the (hardware-specific) masters.
+ *
+ * Copyright (C) IBM Corporation 2016
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef DRIVERS_FSI_MASTER_H
+#define DRIVERS_FSI_MASTER_H
+
+#include <linux/device.h>
+
+struct fsi_master {
+	struct device	*dev;
+	int		idx;
+	int		n_links;
+	int		(*read)(struct fsi_master *, int link,
+				uint8_t slave, uint32_t addr,
+				void *val, size_t size);
+	int		(*write)(struct fsi_master *, int link,
+				uint8_t slave, uint32_t addr,
+				const void *val, size_t size);
+};
+
+extern int fsi_master_register(struct fsi_master *master);
+extern void fsi_master_unregister(struct fsi_master *master);
+
+#endif /* DRIVERS_FSI_MASTER_H */
-- 
1.8.2.2

[PATCH 08/16] drivers/fsi: Add crc4 helpers

[Chris Bostic]

From: Jeremy Kerr <jk@ozlabs.org>

Add some helpers for the crc checks for the slave configuration table.
This works 4-bits-at-a-time, using a simple table approach.

We will need this in the FSI core code, as well as any master
implementations that need to calculate CRCs in software.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
---
 drivers/fsi/fsi-core.c   | 21 +++++++++++++++++++++
 drivers/fsi/fsi-master.h | 21 +++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index ceaf536..f0832c7 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -32,6 +32,27 @@ struct fsi_slave {
 
 #define to_fsi_slave(d) container_of(d, struct fsi_slave, dev)
 
+/* crc helpers */
+static const uint8_t crc4_tab[] = {
+	0x0, 0x7, 0xe, 0x9, 0xb, 0xc, 0x5, 0x2,
+	0x1, 0x6, 0xf, 0x8, 0xa, 0xd, 0x4, 0x3,
+};
+
+uint8_t fsi_crc4(uint8_t c, uint64_t x, int bits)
+{
+	int i;
+
+	/* Align to 4-bits */
+	bits = (bits + 3) & ~0x3;
+
+	/* Calculate crc4 over four-bit nibbles, starting at the MSbit */
+	for (i = bits; i >= 0; i -= 4)
+		c = crc4_tab[c ^ ((x >> i) & 0xf)];
+
+	return c;
+}
+EXPORT_SYMBOL_GPL(fsi_crc4);
+
 /* FSI slave support */
 static int fsi_slave_init(struct fsi_master *master,
 		int link, uint8_t slave_id)
diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h
index e75a810..cafb433 100644
--- a/drivers/fsi/fsi-master.h
+++ b/drivers/fsi/fsi-master.h
@@ -34,4 +34,25 @@ struct fsi_master {
 extern int fsi_master_register(struct fsi_master *master);
 extern void fsi_master_unregister(struct fsi_master *master);
 
+/**
+ * crc4 helper: Given a starting crc4 state @c, calculate the crc4 vaue of @x,
+ * which is @bits in length. This may be required by master implementations
+ * that do not provide their own hardware checksums.
+ *
+ * The crc4 is performed on 4-bit chunks (which is all we need for FSI
+ * calculations). Typically, we'll want a starting state of 0:
+ *
+ *  c = fsi_crc4(0, msg, len);
+ *
+ * To crc4 a message that includes a single start bit, initialise crc4 state
+ * with:
+ *
+ *  c = fsi_crc4(0, 1, 1);
+ *
+ * Then update with message data:
+ *
+ *  c = fsi_crc4(c, msg, len);
+ */
+uint8_t fsi_crc4(uint8_t c, uint64_t x, int bits);
+
 #endif /* DRIVERS_FSI_MASTER_H */
-- 
1.8.2.2

Re: [PATCH 08/16] drivers/fsi: Add crc4 helpers

[Greg KH]

On Tue, Dec 06, 2016 at 08:09:31PM -0600, Chris Bostic wrote:
> From: Jeremy Kerr <jk@ozlabs.org>
> 
> Add some helpers for the crc checks for the slave configuration table.
> This works 4-bits-at-a-time, using a simple table approach.
> 
> We will need this in the FSI core code, as well as any master
> implementations that need to calculate CRCs in software.
> 
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
> Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
> ---
>  drivers/fsi/fsi-core.c   | 21 +++++++++++++++++++++
>  drivers/fsi/fsi-master.h | 21 +++++++++++++++++++++
>  2 files changed, 42 insertions(+)

Why not just create lib/crc4.c with these functions, like the other crc
functions in the kernel?  Don't bury these in some random driver
subsystem please.

thanks,

greg k-h

Re: [PATCH 08/16] drivers/fsi: Add crc4 helpers

[Jeremy Kerr]

Hi Greg,

> Why not just create lib/crc4.c with these functions, like the other crc
> functions in the kernel?

Two (bad) reasons:

 - The crc4 implementation here is pretty specific to the FSI
   usage (only supporting 4-bit-sized chunks), to keep the math & lookup
   table simple

 - I'm lazy

So yes, we should spend the effort now to make this generic enough for
a lib/crc4.c. Would we want to support different values for the
polynomial?

Chris: do you want me to to that, or will you?

Cheers,


Jeremy

Re: [PATCH 08/16] drivers/fsi: Add crc4 helpers

[Christopher Bostic]

On Wed, Dec 7, 2016 at 5:33 PM, Jeremy Kerr <jk@ozlabs.org> wrote:
> Hi Greg,
>
>> Why not just create lib/crc4.c with these functions, like the other crc
>> functions in the kernel?
>
> Two (bad) reasons:
>
>  - The crc4 implementation here is pretty specific to the FSI
>    usage (only supporting 4-bit-sized chunks), to keep the math & lookup
>    table simple
>
>  - I'm lazy
>
> So yes, we should spend the effort now to make this generic enough for
> a lib/crc4.c. Would we want to support different values for the
> polynomial?
>
> Chris: do you want me to to that, or will you?

Hi Jeremy,

I'll take this one.  Will implement as per Greg's suggestions.

Thanks,
Chris

>
> Cheers,
>
>
> Jeremy

[PATCH 09/16] drivers/fsi: Implement slave initialisation

[Chris Bostic]

From: Jeremy Kerr <jk@ozlabs.org>

Create fsi_slave devices during the master scan.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
---
 drivers/fsi/fsi-core.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index f0832c7..aa4330a 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -16,10 +16,14 @@
 #include <linux/device.h>
 #include <linux/fsi.h>
 #include <linux/module.h>
+#include <linux/slab.h>
 
 #include "fsi-master.h"
 
 #define FSI_N_SLAVES	4
+#define FSI_SLAVE_CONF_CRC_SHIFT        4
+#define FSI_SLAVE_CONF_CRC_MASK         0x0000000f
+#define FSI_SLAVE_CONF_DATA_BITS        28
 
 static atomic_t master_idx = ATOMIC_INIT(-1);
 
@@ -54,12 +58,59 @@ uint8_t fsi_crc4(uint8_t c, uint64_t x, int bits)
 EXPORT_SYMBOL_GPL(fsi_crc4);
 
 /* FSI slave support */
+
+static void fsi_slave_release(struct device *dev)
+{
+	struct fsi_slave *slave = to_fsi_slave(dev);
+
+	kfree(slave);
+}
+
 static int fsi_slave_init(struct fsi_master *master,
 		int link, uint8_t slave_id)
 {
-	/* todo: initialise slave device, perform engine scan */
+	struct fsi_slave *slave;
+	uint32_t chip_id;
+	int rc;
+	uint8_t crc;
+
+	rc = master->read(master, link, slave_id, 0, &chip_id, sizeof(chip_id));
+	if (rc) {
+		dev_warn(master->dev, "can't read slave %02x:%02x: %d\n",
+				link, slave_id, rc);
+		return -ENODEV;
+	}
+	crc = fsi_crc4(0, chip_id >> FSI_SLAVE_CONF_CRC_SHIFT,
+			FSI_SLAVE_CONF_DATA_BITS);
+	if (crc != (chip_id & FSI_SLAVE_CONF_CRC_MASK)) {
+		dev_warn(master->dev, "slave %02x:%02x invalid chip id CRC!\n",
+				link, slave_id);
+		return -EIO;
+	}
+
+	pr_debug("fsi: found chip %08x at %02x:%02x:%02x\n",
+			master->idx, chip_id, link, slave_id);
+
+	/* we can communicate with a slave; create devices and scan */
+	slave = kzalloc(sizeof(*slave), GFP_KERNEL);
+	if (!slave)
+		return -ENOMEM;
+
+	slave->master = master;
+	slave->id = slave_id;
+	slave->dev.parent = master->dev;
+	slave->dev.release = fsi_slave_release;
+
+	dev_set_name(&slave->dev, "slave@%02x:%02x", link, slave_id);
+	rc = device_register(&slave->dev);
+	if (rc < 0) {
+		dev_warn(master->dev, "failed to create slave device: %d\n",
+				rc);
+		put_device(&slave->dev);
+		return rc;
+	}
 
-	return -ENODEV;
+	return rc;
 }
 
 /* FSI master support */
-- 
1.8.2.2

[PATCH 11/16] drivers/fsi: Add device read/write/peek functions

[Chris Bostic]

From: Jeremy Kerr <jk@ozlabs.org>

This change introduces the fsi device API: simple read, write and peek
accessors for the devices' address spaces.

Includes contributions from Chris Bostic <cbostic@us.ibm.com>

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
---
 drivers/fsi/fsi-core.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fsi.h    |  7 ++++++-
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index b51ea35..80feeb8 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -33,6 +33,8 @@
 #define FSI_SLAVE_CONF_CRC_MASK		0x0000000f
 #define FSI_SLAVE_CONF_DATA_BITS	28
 
+#define FSI_PEEK_BASE			0x410
+
 static const int engine_page_size = 0x400;
 
 static atomic_t master_idx = ATOMIC_INIT(-1);
@@ -46,8 +48,46 @@ struct fsi_slave {
 
 #define to_fsi_slave(d) container_of(d, struct fsi_slave, dev)
 
+static int fsi_slave_read(struct fsi_slave *slave, uint32_t addr,
+		void *val, size_t size);
+static int fsi_slave_write(struct fsi_slave *slave, uint32_t addr,
+		const void *val, size_t size);
+
 /* FSI endpoint-device support */
 
+int fsi_device_read(struct fsi_device *dev, uint32_t addr, void *val,
+		size_t size)
+{
+	if (addr > dev->size)
+		return -EINVAL;
+
+	if (addr + size > dev->size)
+		return -EINVAL;
+
+	return fsi_slave_read(dev->slave, dev->addr + addr, val, size);
+}
+EXPORT_SYMBOL_GPL(fsi_device_read);
+
+int fsi_device_write(struct fsi_device *dev, uint32_t addr, const void *val,
+		size_t size)
+{
+	if (addr > dev->size)
+		return -EINVAL;
+
+	if (addr + size > dev->size)
+		return -EINVAL;
+
+	return fsi_slave_write(dev->slave, dev->addr + addr, val, size);
+}
+EXPORT_SYMBOL_GPL(fsi_device_write);
+
+int fsi_device_peek(struct fsi_device *dev, void *val)
+{
+	uint32_t addr = FSI_PEEK_BASE + ((dev->unit - 2) * sizeof(uint32_t));
+
+	return fsi_slave_read(dev->slave, addr, val, sizeof(uint32_t));
+}
+
 static void fsi_device_release(struct device *_device)
 {
 	struct fsi_device *device = to_fsi_dev(_device);
@@ -100,6 +140,13 @@ static int fsi_slave_read(struct fsi_slave *slave, uint32_t addr,
 			slave->id, addr, val, size);
 }
 
+static int fsi_slave_write(struct fsi_slave *slave, uint32_t addr,
+			const void *val, size_t size)
+{
+	return slave->master->write(slave->master, slave->link,
+			slave->id, addr, val, size);
+}
+
 static int fsi_slave_scan(struct fsi_slave *slave)
 {
 	uint32_t engine_addr;
diff --git a/include/linux/fsi.h b/include/linux/fsi.h
index efa55ba..66bce48 100644
--- a/include/linux/fsi.h
+++ b/include/linux/fsi.h
@@ -27,6 +27,12 @@ struct fsi_device {
 	uint32_t		size;
 };
 
+extern int fsi_device_read(struct fsi_device *dev, uint32_t addr,
+		void *val, size_t size);
+extern int fsi_device_write(struct fsi_device *dev, uint32_t addr,
+		const void *val, size_t size);
+extern int fsi_device_peek(struct fsi_device *dev, void *val);
+
 struct fsi_device_id {
 	u8	engine_type;
 	u8	version;
@@ -40,7 +46,6 @@ struct fsi_device_id {
 #define FSI_DEVICE_VERSIONED(t, v) \
 	.engine_type = (t), .version = (v),
 
-
 struct fsi_driver {
 	struct device_driver		drv;
 	const struct fsi_device_id	*id_table;
-- 
1.8.2.2

Re: [PATCH 11/16] drivers/fsi: Add device read/write/peek functions

[Greg KH]

On Tue, Dec 06, 2016 at 08:09:33PM -0600, Chris Bostic wrote:
> diff --git a/include/linux/fsi.h b/include/linux/fsi.h
> index efa55ba..66bce48 100644
> --- a/include/linux/fsi.h
> +++ b/include/linux/fsi.h
> @@ -27,6 +27,12 @@ struct fsi_device {
>  	uint32_t		size;
>  };
>  
> +extern int fsi_device_read(struct fsi_device *dev, uint32_t addr,
> +		void *val, size_t size);
> +extern int fsi_device_write(struct fsi_device *dev, uint32_t addr,
> +		const void *val, size_t size);
> +extern int fsi_device_peek(struct fsi_device *dev, void *val);
> +
>  struct fsi_device_id {
>  	u8	engine_type;
>  	u8	version;
> @@ -40,7 +46,6 @@ struct fsi_device_id {
>  #define FSI_DEVICE_VERSIONED(t, v) \
>  	.engine_type = (t), .version = (v),
>  
> -
>  struct fsi_driver {
>  	struct device_driver		drv;
>  	const struct fsi_device_id	*id_table;

Strange whitespace change here :)

Not a real problem, I like the fact that you have broken this down into
very logical pieces making it much easier to review, thanks so much for
doing this.

greg k-h

[PATCH 12/16] drivers/fsi: Set up links for slave communication

[Chris Bostic]

From: Chris Bostic <cbostic@us.ibm.com>

Enable each link and send a break command in preparation
for scanning each link for slaves.

Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
---
 drivers/fsi/fsi-core.c   | 39 ++++++++++++++++++++++++++++++++++++---
 drivers/fsi/fsi-master.h |  2 ++
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index 80feeb8..93de0f1 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -290,16 +290,49 @@ static int fsi_slave_init(struct fsi_master *master,
 
 /* FSI master support */
 
+static int fsi_master_link_enable(struct fsi_master *master, int link)
+{
+	if (master->link_enable)
+		return master->link_enable(master, link);
+
+	return 0;
+}
+
+/*
+ * Issue a break command on this link
+ */
+static int fsi_master_break(struct fsi_master *master, int link)
+{
+	if (master->send_break)
+		return master->send_break(master, link);
+
+	return 0;
+}
+
 static int fsi_master_scan(struct fsi_master *master)
 {
-	int link, slave_id;
+	int link, slave_id, rc;
+
+	for (link = 0; link < master->n_links; link++) {
+		rc = fsi_master_link_enable(master, link);
+		if (rc) {
+			dev_dbg(master->dev,
+				"enable link:%d failed with:%d\n", link, rc);
+			continue;
+		}
+		rc = fsi_master_break(master, link);
+		if (rc) {
+			dev_dbg(master->dev,
+				"Break to link:%d failed with:%d\n", link, rc);
+			continue;
+		}
 
-	for (link = 0; link < master->n_links; link++)
 		for (slave_id = 0; slave_id < FSI_N_SLAVES; slave_id++)
 			fsi_slave_init(master, link, slave_id);
 
-	return 0;
+	}
 
+	return 0;
 }
 
 int fsi_master_register(struct fsi_master *master)
diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h
index cafb433..56aad0e 100644
--- a/drivers/fsi/fsi-master.h
+++ b/drivers/fsi/fsi-master.h
@@ -29,6 +29,8 @@ struct fsi_master {
 	int		(*write)(struct fsi_master *, int link,
 				uint8_t slave, uint32_t addr,
 				const void *val, size_t size);
+	int		(*send_break)(struct fsi_master *, int link);
+	int		(*link_enable)(struct fsi_master *, int link);
 };
 
 extern int fsi_master_register(struct fsi_master *master);
-- 
1.8.2.2

Re: [PATCH 04/16] drivers/fsi: Add fsi master definition

[Greg KH]

On Tue, Dec 06, 2016 at 08:09:30PM -0600, Chris Bostic wrote:
> From: Jeremy Kerr <jk@ozlabs.org>
> 
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
> Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
> ---
>  drivers/fsi/fsi-core.c   | 20 ++++++++++++++++++++
>  drivers/fsi/fsi-master.h | 37 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 57 insertions(+)
>  create mode 100644 drivers/fsi/fsi-master.h
> 
> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
> index 3d55bd5..ce9428d 100644
> --- a/drivers/fsi/fsi-core.c
> +++ b/drivers/fsi/fsi-core.c
> @@ -17,6 +17,26 @@
>  #include <linux/fsi.h>
>  #include <linux/module.h>
>  
> +#include "fsi-master.h"
> +
> +static atomic_t master_idx = ATOMIC_INIT(-1);

You don't really want/need an atomic variable, please use the simple ida
interface instead.

thanks,

greg k-h

Re: [PATCH 04/16] drivers/fsi: Add fsi master definition

[Christopher Bostic]

On Wed, Dec 7, 2016 at 3:06 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Tue, Dec 06, 2016 at 08:09:30PM -0600, Chris Bostic wrote:
>> From: Jeremy Kerr <jk@ozlabs.org>
>>
>> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
>> Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
>> ---
>>  drivers/fsi/fsi-core.c   | 20 ++++++++++++++++++++
>>  drivers/fsi/fsi-master.h | 37 +++++++++++++++++++++++++++++++++++++
>>  2 files changed, 57 insertions(+)
>>  create mode 100644 drivers/fsi/fsi-master.h
>>
>> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
>> index 3d55bd5..ce9428d 100644
>> --- a/drivers/fsi/fsi-core.c
>> +++ b/drivers/fsi/fsi-core.c
>> @@ -17,6 +17,26 @@
>>  #include <linux/fsi.h>
>>  #include <linux/module.h>
>>
>> +#include "fsi-master.h"
>> +
>> +static atomic_t master_idx = ATOMIC_INIT(-1);
>
> You don't really want/need an atomic variable, please use the simple ida
> interface instead.

Greg,

Will make the change to simple ida interface.

Thanks for your feedback,
Chris

>
> thanks,
>
> greg k-h