[PATCH-v5 RESEND 0/5] i2c: pxa: Add support for PXA910 family of device

[PATCH-v5 RESEND 0/5] i2c: pxa: Add support for PXA910 family of device

[Vaibhav Hiremath]

Sorry for not following up on this aggressively, was quit busy with some
other stuff. Resending this patch with Robert's Tested-By.


This patch-series is subset of the original patch-series, submitted
on 14 Jul 2015.
Link to Original Patch-series - https://lkml.org/lkml/2015/7/14/80

The first six patches have been already queued up for upstream. So this
patch-series is respin of remaining 5 patches.

Testing:
  - Basic testing on PMIC device on I2C-0 interface
  - Boot tested on platform based on PXA1928
  - Read few registers of PMIC (RTC, ID, etc...) during boot

V4 => V5
=======
Link to V3: https://lkml.org/lkml/2015/7/14/80
  - Dropped First 6 patches as they are already accepted, queued for upstream
  - Fixed a bug in PATCH [5/5], where for non PXA910 devices it as resulting into
    NULL pointer dereference.


For the record, pasting all the details from original patch-series -

V3 => V4
=======
Link to V3: http://www.spinics.net/lists/devicetree/msg85904.html
  - [PATCH 06/11] Removed unnecessary dev_err on devm_kzalloc() check
  - [PATCH 06/11] Removed return check on platform_get_resource(), as 
    devm_ioremap_resource() does it for us.
    Also, brought up the devm_ioremap_resource() function call in the execution
    sequence, as no point in delaying it if we do not have resource.
    It make sense, after this change.
  - [PATCH 04/11] Typecast changed to 'enum pxa_i2c_types'
    Also updated the subject line "Removed ==> Fix"

V2 => V3
=======
Link to V2: http://www.spinics.net/lists/linux-i2c/msg20059.html
  - Removed PATCH [4/12] related to reset of I2C module.
    Suggested by "Robert Jarzmik"
  - Updated commit description for,
      PATCH [11/12]: Mentioned reasoning about moment of clk_get code.
      PATCH [12/12]: for DT property node.
  - Added Acked by "Robert Jarzmik" to patched which he acked.

V1 => V2:
========
Link to V1 - http://lists.infradead.org/pipermail/linux-arm-kernel/2015-May/347012.html
  - Fixed all comments from "Robert Jarzmik" and "Wolfram Sang"
 - Dropped Patch
     05/12: using core bus reset implementation - under work.
     08/12: NAKed and dropped
 - Separated DT binding patch from driver changes, for easy merge


Vaibhav Hiremath (4):
  Documentation: binding: add new property 'disable_after_xfer' to
    i2c-pxa
  i2c: pxa: Add support for pxa910/988 & new configuration features
  Documentation: binding: add sclk adjustment properties to i2c-pxa
  i2c: pxa: Add ILCR (tLow & tHigh) configuration support

Yi Zhang (1):
  i2c: pxa: enable/disable i2c module across msg xfer

 Documentation/devicetree/bindings/i2c/i2c-pxa.txt |  18 +++
 drivers/i2c/busses/i2c-pxa.c                      | 154 ++++++++++++++++++++--
 2 files changed, 163 insertions(+), 9 deletions(-)

-- 
1.9.1

[PATCH-v5 RESEND 1/5] Documentation: binding: add new property 'disable_after_xfer' to i2c-pxa

[Vaibhav Hiremath]

Driver will now supports enable/disable across msg xfer, which user
can control it by new DT property -

i2c-disable-after-xfer : If set, driver will disable I2C module after msg
 xfer and enable it back before xfer.

Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
---
 Documentation/devicetree/bindings/i2c/i2c-pxa.txt | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-pxa.txt b/Documentation/devicetree/bindings/i2c/i2c-pxa.txt
index 12b78ac..9657db5 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-pxa.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-pxa.txt
@@ -18,6 +18,11 @@ Recommended properties :
    status register of i2c controller instead.
  - mrvl,i2c-fast-mode : Enable fast mode of i2c controller.
 
+Optional properties :
+
+ - i2c-disable-after-xfer : If set, driver will disable I2C module
+   after msg xfer and enable it again before xfer.
+
 Examples:
 	twsi1: i2c@d4011000 {
 		compatible = "mrvl,mmp-twsi";
-- 
1.9.1

[PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across msg xfer

[Vaibhav Hiremath]

From: Yi Zhang <yizhang@marvell.com>

Enable i2c module/unit before transmission and disable when it
finishes.

why?
It's because the i2c bus may be disturbed if the slave device,
typically a touch, powers on.

As we do not want to break slave mode support, this patch introduces
DT property to control disable of the I2C module after xfer in master
mode of operation.

i2c-disable-after-xfer : If set, driver will disable I2C module after
msg xfer

Signed-off-by: Yi Zhang <yizhang@marvell.com>
Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
---
 drivers/i2c/busses/i2c-pxa.c | 43 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 66cf437..abf04f2 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -161,6 +161,7 @@ struct pxa_i2c {
 	unsigned char		master_code;
 	unsigned long		rate;
 	bool			highmode_enter;
+	bool			disable_after_xfer;
 };
 
 #define _IBMR(i2c)	((i2c)->reg_ibmr)
@@ -284,6 +285,24 @@ static void i2c_pxa_scream_blue_murder(struct pxa_i2c *i2c, const char *why)
 static void i2c_pxa_master_complete(struct pxa_i2c *i2c, int ret);
 static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id);
 
+/* enable/disable i2c unit */
+static inline int i2c_pxa_is_enabled(struct pxa_i2c *i2c)
+{
+	return (readl(_ICR(i2c)) & ICR_IUE);
+}
+
+static inline void i2c_pxa_enable(struct pxa_i2c *i2c, bool enable)
+{
+	if (enable) {
+		if (!i2c_pxa_is_enabled(i2c)) {
+			writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
+			udelay(100);
+		}
+	} else {
+		writel(readl(_ICR(i2c)) & ~ICR_IUE, _ICR(i2c));
+	}
+}
+
 static inline int i2c_pxa_is_slavemode(struct pxa_i2c *i2c)
 {
 	return !(readl(_ICR(i2c)) & ICR_SCLE);
@@ -480,8 +499,7 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
 	i2c_pxa_set_slave(i2c, 0);
 
 	/* enable unit */
-	writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
-	udelay(100);
+	i2c_pxa_enable(i2c, true);
 }
 
 
@@ -832,6 +850,9 @@ static int i2c_pxa_pio_xfer(struct i2c_adapter *adap,
 	struct pxa_i2c *i2c = adap->algo_data;
 	int ret, i;
 
+	/* Enable i2c unit */
+	i2c_pxa_enable(i2c, true);
+
 	/* If the I2C controller is disabled we need to reset it
 	  (probably due to a suspend/resume destroying state). We do
 	  this here as we can then avoid worrying about resuming the
@@ -852,6 +873,11 @@ static int i2c_pxa_pio_xfer(struct i2c_adapter *adap,
 	ret = -EREMOTEIO;
  out:
 	i2c_pxa_set_slave(i2c, ret);
+
+	/* disable i2c unit */
+	if (i2c->disable_after_xfer)
+		i2c_pxa_enable(i2c, false);
+
 	return ret;
 }
 
@@ -1067,6 +1093,9 @@ static int i2c_pxa_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num
 	struct pxa_i2c *i2c = adap->algo_data;
 	int ret, i;
 
+	/* Enable i2c unit */
+	i2c_pxa_enable(i2c, true);
+
 	for (i = adap->retries; i >= 0; i--) {
 		ret = i2c_pxa_do_xfer(i2c, msgs, num);
 		if (ret != I2C_RETRY)
@@ -1080,6 +1109,10 @@ static int i2c_pxa_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num
 	ret = -EREMOTEIO;
  out:
 	i2c_pxa_set_slave(i2c, ret);
+	/* disable i2c unit */
+	if (i2c->disable_after_xfer)
+		i2c_pxa_enable(i2c, false);
+
 	return ret;
 }
 
@@ -1120,6 +1153,9 @@ static int i2c_pxa_probe_dt(struct platform_device *pdev, struct pxa_i2c *i2c,
 	/* For device tree we always use the dynamic or alias-assigned ID */
 	i2c->adap.nr = -1;
 
+	i2c->disable_after_xfer = of_property_read_bool(np,
+				"i2c-disable-after-xfer");
+
 	if (of_get_property(np, "mrvl,i2c-polling", NULL))
 		i2c->use_pio = 1;
 	if (of_get_property(np, "mrvl,i2c-fast-mode", NULL))
@@ -1264,6 +1300,9 @@ static int i2c_pxa_probe(struct platform_device *dev)
 
 	platform_set_drvdata(dev, i2c);
 
+	if (i2c->disable_after_xfer)
+		i2c_pxa_enable(i2c, false);
+
 #ifdef CONFIG_I2C_PXA_SLAVE
 	dev_info(&i2c->adap.dev, " PXA I2C adapter, slave address %d\n",
 		i2c->slave_addr);
-- 
1.9.1

Re: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across msg xfer

[Wolfram Sang]

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On Mon, Aug 24, 2015 at 11:29:35AM +0530, Vaibhav Hiremath wrote:
> From: Yi Zhang <yizhang@marvell.com>
> 
> Enable i2c module/unit before transmission and disable when it
> finishes.
> 
> why?
> It's because the i2c bus may be disturbed if the slave device,
> typically a touch, powers on.

I am not convinced, "may disturb" is too weak for me. It would need a
way more detailed description of the problem which makes clear that
this mechanism is the only way to go forward.

Can't you use Runtime PM for that?


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Re: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across msg xfer

[Vaibhav Hiremath]

On Saturday 12 September 2015 12:23 AM, Wolfram Sang wrote:
> On Mon, Aug 24, 2015 at 11:29:35AM +0530, Vaibhav Hiremath wrote:
>> From: Yi Zhang <yizhang@marvell.com>
>>
>> Enable i2c module/unit before transmission and disable when it
>> finishes.
>>
>> why?
>> It's because the i2c bus may be disturbed if the slave device,
>> typically a touch, powers on.
>
> I am not convinced, "may disturb" is too weak for me. It would need a
> way more detailed description of the problem which makes clear that
> this mechanism is the only way to go forward.
>

Hmm, Ok.
Not sure what else I can bring up here.

> Can't you use Runtime PM for that?
>

I haven't tried it though, I can give a try and check.

Thanks,
Vaibhav

Re: [PATCH-v5 RESEND 2/5] i2c: pxa: enable/disable i2c module across msg xfer

[Wolfram Sang]

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> >>Enable i2c module/unit before transmission and disable when it
> >>finishes.
> 
> >Can't you use Runtime PM for that?
> >
> 
> I haven't tried it though, I can give a try and check.

It should work. Other I2C drivers are doing exactly that.


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[PATCH-v5 RESEND 3/5] i2c: pxa: Add support for pxa910/988 & new configuration features

[Vaibhav Hiremath]

TWSI_ILCR & TWSI_IWCR registers are used to adjust clock rate
of standard & fast mode in pxa910/988; so this patch adds these two new
entries to "struct pxa_reg_layout" and "struct pxa_i2c".

As discussed in the previous patch-series, the idea here is to add standard
DT properties for ilcr and iwcr configuration fields.
In case of Master ilcr is used for low/high time and in case of slave mode
of operation iwcr is used for setup/hold time.

Signed-off-by: Jett.Zhou <jtzhou@marvell.com>
Signed-off-by: Yi Zhang <yizhang@marvell.com>
Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
---
 drivers/i2c/busses/i2c-pxa.c | 42 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index abf04f2..8d76197 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -46,12 +46,15 @@ struct pxa_reg_layout {
 	u32 icr;
 	u32 isr;
 	u32 isar;
+	u32 ilcr;
+	u32 iwcr;
 };
 
 enum pxa_i2c_types {
 	REGS_PXA2XX,
 	REGS_PXA3XX,
 	REGS_CE4100,
+	REGS_PXA910,
 };
 
 /*
@@ -79,12 +82,22 @@ static struct pxa_reg_layout pxa_reg_layout[] = {
 		.isr =	0x04,
 		/* no isar register */
 	},
+	[REGS_PXA910] = {
+		.ibmr = 0x00,
+		.idbr = 0x08,
+		.icr =	0x10,
+		.isr =	0x18,
+		.isar = 0x20,
+		.ilcr = 0x28,
+		.iwcr = 0x30,
+	},
 };
 
 static const struct platform_device_id i2c_pxa_id_table[] = {
 	{ "pxa2xx-i2c",		REGS_PXA2XX },
 	{ "pxa3xx-pwri2c",	REGS_PXA3XX },
 	{ "ce4100-i2c",		REGS_CE4100 },
+	{ "pxa910-i2c",		REGS_PXA910 },
 	{ },
 };
 MODULE_DEVICE_TABLE(platform, i2c_pxa_id_table);
@@ -124,6 +137,24 @@ MODULE_DEVICE_TABLE(platform, i2c_pxa_id_table);
 #define ISR_SAD		(1 << 9)	   /* slave address detected */
 #define ISR_BED		(1 << 10)	   /* bus error no ACK/NAK */
 
+/* bit field shift & mask */
+#define ILCR_SLV_SHIFT		0
+#define ILCR_SLV_MASK		(0x1FF << ILCR_SLV_SHIFT)
+#define ILCR_FLV_SHIFT		9
+#define ILCR_FLV_MASK		(0x1FF << ILCR_FLV_SHIFT)
+#define ILCR_HLVL_SHIFT		18
+#define ILCR_HLVL_MASK		(0x1FF << ILCR_HLVL_SHIFT)
+#define ILCR_HLVH_SHIFT		27
+#define ILCR_HLVH_MASK		(0x1F << ILCR_HLVH_SHIFT)
+
+#define IWCR_CNT_SHIFT		0
+#define IWCR_CNT_MASK		(0x1F << IWCR_CNT_SHIFT)
+#define IWCR_HS_CNT1_SHIFT	5
+#define IWCR_HS_CNT1_MASK	(0x1F << IWCR_HS_CNT1_SHIFT)
+#define IWCR_HS_CNT2_SHIFT	10
+#define IWCR_HS_CNT2_MASK	(0x1F << IWCR_HS_CNT2_SHIFT)
+
+
 struct pxa_i2c {
 	spinlock_t		lock;
 	wait_queue_head_t	wait;
@@ -150,6 +181,8 @@ struct pxa_i2c {
 	void __iomem		*reg_icr;
 	void __iomem		*reg_isr;
 	void __iomem		*reg_isar;
+	void __iomem		*reg_ilcr;
+	void __iomem		*reg_iwcr;
 
 	unsigned long		iobase;
 	unsigned long		iosize;
@@ -169,6 +202,8 @@ struct pxa_i2c {
 #define _ICR(i2c)	((i2c)->reg_icr)
 #define _ISR(i2c)	((i2c)->reg_isr)
 #define _ISAR(i2c)	((i2c)->reg_isar)
+#define _ILCR(i2c)	((i2c)->reg_ilcr)
+#define _IWCR(i2c)	((i2c)->reg_iwcr)
 
 /*
  * I2C Slave mode address
@@ -1135,7 +1170,7 @@ static const struct i2c_algorithm i2c_pxa_pio_algorithm = {
 static const struct of_device_id i2c_pxa_dt_ids[] = {
 	{ .compatible = "mrvl,pxa-i2c", .data = (void *)REGS_PXA2XX },
 	{ .compatible = "mrvl,pwri2c", .data = (void *)REGS_PXA3XX },
-	{ .compatible = "mrvl,mmp-twsi", .data = (void *)REGS_PXA2XX },
+	{ .compatible = "mrvl,mmp-twsi", .data = (void *)REGS_PXA910 },
 	{}
 };
 MODULE_DEVICE_TABLE(of, i2c_pxa_dt_ids);
@@ -1243,6 +1278,11 @@ static int i2c_pxa_probe(struct platform_device *dev)
 	if (i2c_type != REGS_CE4100)
 		i2c->reg_isar = i2c->reg_base + pxa_reg_layout[i2c_type].isar;
 
+	if (i2c_type == REGS_PXA910) {
+		i2c->reg_ilcr = i2c->reg_base + pxa_reg_layout[i2c_type].ilcr;
+		i2c->reg_iwcr = i2c->reg_base + pxa_reg_layout[i2c_type].iwcr;
+	}
+
 	i2c->iobase = res->start;
 	i2c->iosize = resource_size(res);
 
-- 
1.9.1

Re: [PATCH-v5 RESEND 3/5] i2c: pxa: Add support for pxa910/988 & new configuration features

[Wolfram Sang]

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On Mon, Aug 24, 2015 at 11:29:36AM +0530, Vaibhav Hiremath wrote:
> TWSI_ILCR & TWSI_IWCR registers are used to adjust clock rate
> of standard & fast mode in pxa910/988; so this patch adds these two new
> entries to "struct pxa_reg_layout" and "struct pxa_i2c".
> 
> As discussed in the previous patch-series, the idea here is to add standard
> DT properties for ilcr and iwcr configuration fields.
> In case of Master ilcr is used for low/high time and in case of slave mode
> of operation iwcr is used for setup/hold time.

I need to rethink how to describe i2c bus timing parameters in DT in the
next days. But this is planned for 4.4., promised.

One thing I already wonder about this one...

>  static const struct platform_device_id i2c_pxa_id_table[] = {
>  	{ "pxa2xx-i2c",		REGS_PXA2XX },
>  	{ "pxa3xx-pwri2c",	REGS_PXA3XX },
>  	{ "ce4100-i2c",		REGS_CE4100 },
> +	{ "pxa910-i2c",		REGS_PXA910 },
>  	{ },

You add a new platform_id...

> @@ -1135,7 +1170,7 @@ static const struct i2c_algorithm i2c_pxa_pio_algorithm = {
>  static const struct of_device_id i2c_pxa_dt_ids[] = {
>  	{ .compatible = "mrvl,pxa-i2c", .data = (void *)REGS_PXA2XX },
>  	{ .compatible = "mrvl,pwri2c", .data = (void *)REGS_PXA3XX },
> -	{ .compatible = "mrvl,mmp-twsi", .data = (void *)REGS_PXA2XX },
> +	{ .compatible = "mrvl,mmp-twsi", .data = (void *)REGS_PXA910 },
>  	{}

...but change the compatible binding instead of adding a new one?


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Re: [PATCH-v5 RESEND 3/5] i2c: pxa: Add support for pxa910/988 & new configuration features

[Vaibhav Hiremath]

On Saturday 12 September 2015 12:36 AM, Wolfram Sang wrote:
> On Mon, Aug 24, 2015 at 11:29:36AM +0530, Vaibhav Hiremath wrote:
>> TWSI_ILCR & TWSI_IWCR registers are used to adjust clock rate
>> of standard & fast mode in pxa910/988; so this patch adds these two new
>> entries to "struct pxa_reg_layout" and "struct pxa_i2c".
>>
>> As discussed in the previous patch-series, the idea here is to add standard
>> DT properties for ilcr and iwcr configuration fields.
>> In case of Master ilcr is used for low/high time and in case of slave mode
>> of operation iwcr is used for setup/hold time.
>
> I need to rethink how to describe i2c bus timing parameters in DT in the
> next days. But this is planned for 4.4., promised.
>
> One thing I already wonder about this one...
>
>>   static const struct platform_device_id i2c_pxa_id_table[] = {
>>   	{ "pxa2xx-i2c",		REGS_PXA2XX },
>>   	{ "pxa3xx-pwri2c",	REGS_PXA3XX },
>>   	{ "ce4100-i2c",		REGS_CE4100 },
>> +	{ "pxa910-i2c",		REGS_PXA910 },
>>   	{ },
>
> You add a new platform_id...
>
>> @@ -1135,7 +1170,7 @@ static const struct i2c_algorithm i2c_pxa_pio_algorithm = {
>>   static const struct of_device_id i2c_pxa_dt_ids[] = {
>>   	{ .compatible = "mrvl,pxa-i2c", .data = (void *)REGS_PXA2XX },
>>   	{ .compatible = "mrvl,pwri2c", .data = (void *)REGS_PXA3XX },
>> -	{ .compatible = "mrvl,mmp-twsi", .data = (void *)REGS_PXA2XX },
>> +	{ .compatible = "mrvl,mmp-twsi", .data = (void *)REGS_PXA910 },
>>   	{}
>
> ...but change the compatible binding instead of adding a new one?
>

Yes, because the offset for both REGS_PXA2XX and REGS_PXA910 are same,
and for REGS_PXA2XX we already have compatible entry "mrvl,pxa-i2c".
And the i2c binding documentation, which says,
for platforms using REGS_PXA2XX, they need to provide additional node
"mrvl,pxa-i2c". Which is confusing :)

Also, when I did git-blame on the driver file to see why "mmp-twsi"
entry has been added without anyone really using it. But I did not find
anything meaningful.
So, from the code it was very clear that, "mmp-twsi" and "pxa-i2c" both
are same, its the code which I am adding here brings difference between 
them.

I tried to find datasheet for the platforms using "mmp-twsi", but was
unlucky.


Thanks,
Vaibhav




Thanks,
Vaibhav

Re: [PATCH-v5 RESEND 3/5] i2c: pxa: Add support for pxa910/988 & new configuration features

[Wolfram Sang]

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> And the i2c binding documentation, which says,
> for platforms using REGS_PXA2XX, they need to provide additional node
> "mrvl,pxa-i2c". Which is confusing :)

Yes, the description of the compatible entry is pretty bogus. Could you
fix that?


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Re: [PATCH-v5 RESEND 3/5] i2c: pxa: Add support for pxa910/988 & new configuration features

[Wolfram Sang]

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On Mon, Aug 24, 2015 at 11:29:36AM +0530, Vaibhav Hiremath wrote:
> TWSI_ILCR & TWSI_IWCR registers are used to adjust clock rate
> of standard & fast mode in pxa910/988; so this patch adds these two new
> entries to "struct pxa_reg_layout" and "struct pxa_i2c".
> 
> As discussed in the previous patch-series, the idea here is to add standard
> DT properties for ilcr and iwcr configuration fields.
> In case of Master ilcr is used for low/high time and in case of slave mode
> of operation iwcr is used for setup/hold time.
> 
> Signed-off-by: Jett.Zhou <jtzhou@marvell.com>
> Signed-off-by: Yi Zhang <yizhang@marvell.com>
> Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
> Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>

Fixed this checkpatch warning:

CHECK: Please don't use multiple blank lines
#82: FILE: drivers/i2c/busses/i2c-pxa.c:157:
+
+

and applied to for-next, thanks!


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[PATCH-v5 RESEND 4/5] Documentation: binding: add sclk adjustment properties to i2c-pxa

[Vaibhav Hiremath]

With addition of PXA910 family of devices, the TWSI module supports
new feature which allows us to adjust SCLK. i2c-pxa driver takes input
configuration in nsec and converts it to respective bit-fields,

 - i2c-sclk-low-time-ns : SCLK low time (tlow)
   This property is used along with mode selection.
 - i2c-sclk-high-time-ns : SCLK high time (thigh)
 - i2c-start-hold-time-ns : Used in case of high speed mode for start bit
   hold/setup wait counter.
 - i2c-stop-hold-time-ns : Used in case of high speed mode for stop bit
   hold/setup wait counter.
 - i2c-sda-hold-time-ns : Used to calculate hold/setup wait counter for
   standard and fast mode.

Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
---
 Documentation/devicetree/bindings/i2c/i2c-pxa.txt | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-pxa.txt b/Documentation/devicetree/bindings/i2c/i2c-pxa.txt
index 9657db5..bb4df60 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-pxa.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-pxa.txt
@@ -23,12 +23,25 @@ Optional properties :
  - i2c-disable-after-xfer : If set, driver will disable I2C module
    after msg xfer and enable it again before xfer.
 
+   (Applicable to PXA910 family):
+
+ - i2c-sclk-low-time-ns : SCLK low time (tlow), for standard/fast/high
+   speed mode.
+   This property is used along with mode selection. Driver uses this property
+   to set low/high time for standard and fast speed mode, as HW counter
+   bit-field is same for both.
+ - i2c-sclk-high-time-ns : SCLK high time (thigh), Used in case of high speed
+   mode only.
+
 Examples:
 	twsi1: i2c@d4011000 {
 		compatible = "mrvl,mmp-twsi";
 		reg = <0xd4011000 0x1000>;
 		interrupts = <7>;
 		mrvl,i2c-fast-mode;
+
+		i2c-sclk-low-time-ns = <988>;
+		i2c-sclk-high-time-ns = <988>;
 	};
 	
 	twsi2: i2c@d4025000 {
-- 
1.9.1

Re: [PATCH-v5 RESEND 4/5] Documentation: binding: add sclk adjustment properties to i2c-pxa

[Wolfram Sang]

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On Mon, Aug 24, 2015 at 11:29:37AM +0530, Vaibhav Hiremath wrote:
> With addition of PXA910 family of devices, the TWSI module supports
> new feature which allows us to adjust SCLK. i2c-pxa driver takes input
> configuration in nsec and converts it to respective bit-fields,
> 
>  - i2c-sclk-low-time-ns : SCLK low time (tlow)
>    This property is used along with mode selection.
>  - i2c-sclk-high-time-ns : SCLK high time (thigh)
>  - i2c-start-hold-time-ns : Used in case of high speed mode for start bit
>    hold/setup wait counter.
>  - i2c-stop-hold-time-ns : Used in case of high speed mode for stop bit
>    hold/setup wait counter.
>  - i2c-sda-hold-time-ns : Used to calculate hold/setup wait counter for
>    standard and fast mode.
> 
> Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>

Ooookay, after checking some datasheets, I finally stumbled over the
fact that this driver is not using "clock-frequency" to determine the
bus speed. However, this is the standard way of defining that in DT, so
this driver should adhere to that, too, and not invent something new.
Previously, I was under the impression that the above parameters were
needed for fine-tuning and couldn't fully grasp why. But this is for
defining the bus speed which is a no-go.

It looks to me that older PXA only have a bit to select between 100 and
400kHz while this newer one can have arbitrary frequencies. Correct?

So, what the driver should do:

- Keep support for the old "mrvl,i2c-fast-mode" binding which should be
  marked as deprecated

- get the value of the standard property "clock-frequency"

- for old PXAs, complain if not 100 or 400kHz, otherwise set the bit
  accordingly

- for new PXAs, calculate the ilcr and iwcr values from
  "clock-frequency"

Makes sense?

Regards,

   Wolfram


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[PATCH-v5 RESEND 5/5] i2c: pxa: Add ILCR (tLow & tHigh) configuration support

[Vaibhav Hiremath]

With addition of PXA910 family of devices, the TWSI module supports
SCL clock adjustment using ILCR register.

This patch enables the control and configuration of ICLR through DT
properties,

i2c-sclk-high-time-ns:
  SCLK high time (tHigh), for standard/fast/high speed mode
i2c-sclk-low-time-ns:
  SCLK low time (tLow), for standard/fast/high speed mode

Note that in case of standard and fast mod, the tLow and tHigh counters
are same, and software will use tLow value.

Also, brought up devm_clk_get() fn above i2c_pxa_probe_dt(), as it
uses clk rate for timing calculations.

Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Signed-off-by: Jett.Zhou <jtzhou@marvell.com>
Signed-off-by: Yi Zhang <yizhang@marvell.com>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
---
 drivers/i2c/busses/i2c-pxa.c | 69 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 63 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 8d76197..6012ae5 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -195,6 +195,9 @@ struct pxa_i2c {
 	unsigned long		rate;
 	bool			highmode_enter;
 	bool			disable_after_xfer;
+
+	unsigned int		sclk_thigh_load_cnt;
+	unsigned int		sclk_tlow_load_cnt;
 };
 
 #define _IBMR(i2c)	((i2c)->reg_ibmr)
@@ -507,6 +510,36 @@ static void i2c_pxa_set_slave(struct pxa_i2c *i2c, int errcode)
 #define i2c_pxa_set_slave(i2c, err)	do { } while (0)
 #endif
 
+static void i2c_pxa_do_sclk_adj(struct pxa_i2c *i2c)
+{
+	unsigned int reg_ilcr;
+
+	if (!i2c->reg_ilcr)
+		return;
+
+	reg_ilcr = readl(_ILCR(i2c));
+
+	/* For standard/fast mode tlow and thigh counters are same */
+	if (i2c->sclk_tlow_load_cnt) {
+		unsigned int mask, shift;
+
+		mask = i2c->high_mode ? ILCR_HLVL_MASK :
+			i2c->fast_mode ? ILCR_FLV_MASK : ILCR_SLV_MASK;
+		shift = i2c->high_mode ? ILCR_HLVL_SHIFT :
+			i2c->fast_mode ? ILCR_FLV_SHIFT : ILCR_SLV_SHIFT;
+
+		reg_ilcr &= ~mask;
+		reg_ilcr |= i2c->sclk_tlow_load_cnt << shift;
+	}
+
+	if (i2c->high_mode && i2c->sclk_thigh_load_cnt) {
+		reg_ilcr &= ~ILCR_HLVH_MASK;
+		reg_ilcr |= i2c->sclk_thigh_load_cnt << ILCR_HLVH_SHIFT;
+	}
+
+	writel(reg_ilcr, _ILCR(i2c));
+}
+
 static void i2c_pxa_reset(struct pxa_i2c *i2c)
 {
 	pr_debug("Resetting I2C Controller Unit\n");
@@ -526,6 +559,8 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
 	writel(I2C_ICR_INIT | (i2c->fast_mode ? ICR_FM : 0), _ICR(i2c));
 	writel(readl(_ICR(i2c)) | (i2c->high_mode ? ICR_HS : 0), _ICR(i2c));
 
+	i2c_pxa_do_sclk_adj(i2c);
+
 #ifdef CONFIG_I2C_PXA_SLAVE
 	dev_info(&i2c->adap.dev, "Enabling slave mode\n");
 	writel(readl(_ICR(i2c)) | ICR_SADIE | ICR_ALDIE | ICR_SSDIE, _ICR(i2c));
@@ -1198,6 +1233,26 @@ static int i2c_pxa_probe_dt(struct platform_device *pdev, struct pxa_i2c *i2c,
 
 	*i2c_types = (enum pxa_i2c_types)(of_id->data);
 
+	/* optional properties */
+	if (of_device_is_compatible(np, "mrvl,mmp-twsi")) {
+		unsigned int tlow = 0, thigh = 0;
+		unsigned int clk_ns;
+
+		/* clock time in nsec */
+		clk_ns = 1000000 / (i2c->rate / 1000);
+
+		of_property_read_u32(np, "i2c-sclk-high-time-ns", &thigh);
+		i2c->sclk_thigh_load_cnt = thigh / clk_ns;
+
+		of_property_read_u32(np, "i2c-sclk-low-time-ns", &tlow);
+		i2c->sclk_tlow_load_cnt = tlow / clk_ns;
+
+		/* For std/fast mode tlow & thigh have same bit-fields */
+		if (!i2c->high_mode &&
+			(i2c->sclk_tlow_load_cnt != i2c->sclk_thigh_load_cnt))
+			dev_warn(&i2c->adap.dev,
+				"mismatch of tLow & tHigh values, using tLow\n");
+	}
 	return 0;
 }
 
@@ -1248,6 +1303,14 @@ static int i2c_pxa_probe(struct platform_device *dev)
 		return irq;
 	}
 
+	i2c->clk = devm_clk_get(&dev->dev, NULL);
+	if (IS_ERR(i2c->clk)) {
+		dev_err(&dev->dev, "failed to get the clk: %ld\n", PTR_ERR(i2c->clk));
+		return PTR_ERR(i2c->clk);
+	}
+
+	i2c->rate = clk_get_rate(i2c->clk);
+
 	/* Default adapter num to device id; i2c_pxa_probe_dt can override. */
 	i2c->adap.nr = dev->id;
 
@@ -1265,12 +1328,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
 
 	strlcpy(i2c->adap.name, "pxa_i2c-i2c", sizeof(i2c->adap.name));
 
-	i2c->clk = devm_clk_get(&dev->dev, NULL);
-	if (IS_ERR(i2c->clk)) {
-		dev_err(&dev->dev, "failed to get the clk: %ld\n", PTR_ERR(i2c->clk));
-		return PTR_ERR(i2c->clk);
-	}
-
 	i2c->reg_ibmr = i2c->reg_base + pxa_reg_layout[i2c_type].ibmr;
 	i2c->reg_idbr = i2c->reg_base + pxa_reg_layout[i2c_type].idbr;
 	i2c->reg_icr = i2c->reg_base + pxa_reg_layout[i2c_type].icr;
-- 
1.9.1

Re: [PATCH-v5 RESEND 0/5] i2c: pxa: Add support for PXA910 family of device

[Vaibhav Hiremath]

On Monday 24 August 2015 11:29 AM, Vaibhav Hiremath wrote:
> Sorry for not following up on this aggressively, was quit busy with some
> other stuff. Resending this patch with Robert's Tested-By.
>
>
> This patch-series is subset of the original patch-series, submitted
> on 14 Jul 2015.
> Link to Original Patch-series - https://lkml.org/lkml/2015/7/14/80
>
> The first six patches have been already queued up for upstream. So this
> patch-series is respin of remaining 5 patches.
>
> Testing:
>    - Basic testing on PMIC device on I2C-0 interface
>    - Boot tested on platform based on PXA1928
>    - Read few registers of PMIC (RTC, ID, etc...) during boot
>
> V4 => V5
> =======
> Link to V3: https://lkml.org/lkml/2015/7/14/80
>    - Dropped First 6 patches as they are already accepted, queued for upstream
>    - Fixed a bug in PATCH [5/5], where for non PXA910 devices it as resulting into
>      NULL pointer dereference.
>
>


Any update on this? This series is waiting since long time now.

Wolfram,
I know you wanted to have more discussion on DT properties & changes.
And I would be more happy to discuss.

Thanks,
Vaibhav