[PATCH] i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20

[PATCH] i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20

[Laxman Dewangan]

Tegra20 i2c controller does not support the continue transfer
which implements the I2C_M_NOSTART functionality of i2c
protocol mangling.
Removing the I2C_M_NOSTART functionality for Tegra20.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reported-by: Stephen Warren <swarren@nvidia.com>
---
 drivers/i2c/busses/i2c-tegra.c |   71 ++++++++++++++++++++++++++++++++--------
 1 files changed, 57 insertions(+), 14 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 66eb53f..11b0c5c 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -27,6 +27,7 @@
 #include <linux/slab.h>
 #include <linux/i2c-tegra.h>
 #include <linux/of_i2c.h>
+#include <linux/of_device.h>
 #include <linux/module.h>
 
 #include <asm/unaligned.h>
@@ -114,6 +115,15 @@ enum msg_end_type {
 };
 
 /**
+ * struct tegra_i2c_hw_feature : Different HW support on Tegra
+ * @has_continue_xfer_support: Continue transfer supports.
+ */
+
+struct tegra_i2c_hw_feature {
+	bool has_continue_xfer_support;
+};
+
+/**
  * struct tegra_i2c_dev	- per device i2c context
  * @dev: device reference for power management
  * @adapter: core i2c layer adapter information
@@ -148,6 +158,7 @@ struct tegra_i2c_dev {
 	int msg_read;
 	unsigned long bus_clk_rate;
 	bool is_suspended;
+	bool has_continue_xfer_support;
 };
 
 static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val, unsigned long reg)
@@ -563,6 +574,16 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 	if (i2c_dev->is_suspended)
 		return -EBUSY;
 
+	/* Support I2C_M_NOSTART only if HW support continue xfer. */
+	for (i = 0; i < num - 1; i++) {
+		if ((msgs[i + 1].flags & I2C_M_NOSTART) &&
+			!i2c_dev->has_continue_xfer_support) {
+			dev_err(i2c_dev->dev,
+				"mesg %d have illegal flag\n", i + 1);
+			return -EINVAL;
+		}
+	}
+
 	clk_prepare_enable(i2c_dev->clk);
 	for (i = 0; i < num; i++) {
 		enum msg_end_type end_type = MSG_END_STOP;
@@ -582,8 +603,13 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 
 static u32 tegra_i2c_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
-		I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_NOSTART;
+	struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
+	u32 ret = I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
+				I2C_FUNC_PROTOCOL_MANGLING;
+
+	if (i2c_dev->has_continue_xfer_support)
+		ret |= I2C_FUNC_NOSTART;
+	return ret;
 }
 
 static const struct i2c_algorithm tegra_i2c_algo = {
@@ -591,6 +617,25 @@ static const struct i2c_algorithm tegra_i2c_algo = {
 	.functionality	= tegra_i2c_func,
 };
 
+static struct tegra_i2c_hw_feature tegra20_i2c_hw = {
+	.has_continue_xfer_support = false,
+};
+
+static struct tegra_i2c_hw_feature tegra30_i2c_hw = {
+	.has_continue_xfer_support = true,
+};
+
+#if defined(CONFIG_OF)
+/* Match table for of_platform binding */
+static const struct of_device_id tegra_i2c_of_match[] __devinitconst = {
+	{ .compatible = "nvidia,tegra30-i2c", .data = &tegra30_i2c_hw, },
+	{ .compatible = "nvidia,tegra20-i2c", .data = &tegra20_i2c_hw, },
+	{ .compatible = "nvidia,tegra20-i2c-dvc", .data = &tegra20_i2c_hw, },
+	{},
+};
+MODULE_DEVICE_TABLE(of, tegra_i2c_of_match);
+#endif
+
 static int __devinit tegra_i2c_probe(struct platform_device *pdev)
 {
 	struct tegra_i2c_dev *i2c_dev;
@@ -600,6 +645,7 @@ static int __devinit tegra_i2c_probe(struct platform_device *pdev)
 	struct clk *i2c_clk;
 	const unsigned int *prop;
 	void __iomem *base;
+	const struct tegra_i2c_hw_feature *hw = &tegra20_i2c_hw;
 	int irq;
 	int ret = 0;
 
@@ -659,11 +705,18 @@ static int __devinit tegra_i2c_probe(struct platform_device *pdev)
 			i2c_dev->bus_clk_rate = be32_to_cpup(prop);
 	}
 
-	if (pdev->dev.of_node)
+	if (pdev->dev.of_node) {
+		const struct of_device_id *match;
+		match = of_match_device(of_match_ptr(tegra_i2c_of_match),
+						&pdev->dev);
+		hw = match->data;
 		i2c_dev->is_dvc = of_device_is_compatible(pdev->dev.of_node,
 						"nvidia,tegra20-i2c-dvc");
-	else if (pdev->id == 3)
+	} else if (pdev->id == 3) {
 		i2c_dev->is_dvc = 1;
+	}
+
+	i2c_dev->has_continue_xfer_support = hw->has_continue_xfer_support;
 	init_completion(&i2c_dev->msg_complete);
 
 	platform_set_drvdata(pdev, i2c_dev);
@@ -751,16 +804,6 @@ static SIMPLE_DEV_PM_OPS(tegra_i2c_pm, tegra_i2c_suspend, tegra_i2c_resume);
 #define TEGRA_I2C_PM	NULL
 #endif
 
-#if defined(CONFIG_OF)
-/* Match table for of_platform binding */
-static const struct of_device_id tegra_i2c_of_match[] __devinitconst = {
-	{ .compatible = "nvidia,tegra20-i2c", },
-	{ .compatible = "nvidia,tegra20-i2c-dvc", },
-	{},
-};
-MODULE_DEVICE_TABLE(of, tegra_i2c_of_match);
-#endif
-
 static struct platform_driver tegra_i2c_driver = {
 	.probe   = tegra_i2c_probe,
 	.remove  = __devexit_p(tegra_i2c_remove),
-- 
1.7.1.1

Re: [PATCH] i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20

[Stephen Warren]

On 08/14/2012 03:19 AM, Laxman Dewangan wrote:
> Tegra20 i2c controller does not support the continue transfer
> which implements the I2C_M_NOSTART functionality of i2c
> protocol mangling.
> Removing the I2C_M_NOSTART functionality for Tegra20.
> 
> Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
> Reported-by: Stephen Warren <swarren@nvidia.com>

Tested-by: Stephen Warren <swarren@wwwdotorg.org>

Note that if I take Laxman's I2C driver clock patches through the Tegra
tree, and Wolfram takes this patch through the I2C tree, there will be a
very slight conflict, since adjacent lines are touched. However, the
resolution is simple and obvious, so I think that's fine.

Re: [PATCH] i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20

[Laxman Dewangan]

On Tuesday 14 August 2012 10:19 PM, Stephen Warren wrote:
> On 08/14/2012 03:19 AM, Laxman Dewangan wrote:
>> Tegra20 i2c controller does not support the continue transfer
>> which implements the I2C_M_NOSTART functionality of i2c
>> protocol mangling.
>> Removing the I2C_M_NOSTART functionality for Tegra20.
>>
>> Signed-off-by: Laxman Dewangan<ldewangan@nvidia.com>
>> Reported-by: Stephen Warren<swarren@nvidia.com>
> Tested-by: Stephen Warren<swarren@wwwdotorg.org>
>
> Note that if I take Laxman's I2C driver clock patches through the Tegra
> tree, and Wolfram takes this patch through the I2C tree, there will be a
> very slight conflict, since adjacent lines are touched. However, the
> resolution is simple and obvious, so I think that's fine.

Stephen/Wolfram,
I have 2 more change to implement runtime PM and dynamic clock control 
for fast clock which I have planned for 3.7.
I think it will be better if this also goes on same tree where the clock 
related change are available to avoid the merge conflict.

Re: [PATCH] i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20

[Stephen Warren]

On 08/16/2012 01:07 AM, Laxman Dewangan wrote:
> On Tuesday 14 August 2012 10:19 PM, Stephen Warren wrote:
>> On 08/14/2012 03:19 AM, Laxman Dewangan wrote:
>>> Tegra20 i2c controller does not support the continue transfer
>>> which implements the I2C_M_NOSTART functionality of i2c
>>> protocol mangling.
>>> Removing the I2C_M_NOSTART functionality for Tegra20.
>>>
>>> Signed-off-by: Laxman Dewangan<ldewangan@nvidia.com>
>>> Reported-by: Stephen Warren<swarren@nvidia.com>
>> Tested-by: Stephen Warren<swarren@wwwdotorg.org>
>>
>> Note that if I take Laxman's I2C driver clock patches through the Tegra
>> tree, and Wolfram takes this patch through the I2C tree, there will be a
>> very slight conflict, since adjacent lines are touched. However, the
>> resolution is simple and obvious, so I think that's fine.
> 
> Stephen/Wolfram,
> I have 2 more change to implement runtime PM and dynamic clock control
> for fast clock which I have planned for 3.7.
> I think it will be better if this also goes on same tree where the clock
> related change are available to avoid the merge conflict.

OK, I guess I can take all the Tegra I2C driver changes through the
Tegra tree if needed. This patch is less trivial than the last, so I
would definitely need Wolfram's ack to do so. I suppose if this ends up
conflicting with e.g. any core work in the I2C tree, I can always give
Wolfram a Tegra branch to merge in first to avoid any issues; If needed,
I'd rather wait until after rc2 or perhaps rc3 before doing that though.