Add EyeQ6H support to the nmk-i2c AMBA driver. It shares the same quirk
as EyeQ5: the memory bus only supports 32-bit accesses. Avoid writeb()
and readb() by reusing the same `priv->has_32b_bus` flag.

It does NOT need to write speed-mode specific value into a register;
therefore it does not depend on the mobileye,olb DT property.

Refactoring is done using is_eyeq5 and is_eyeq6h boolean local
variables. Sort variables in reverse christmas tree to try and
introduce some logic into the ordering.

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
---
 drivers/i2c/busses/i2c-nomadik.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
index ad0f02acdb1215a1c04729f97bb14a4d93f88456..ea511d3a58073eaedb63850026e05b59427a69c6 100644
--- a/drivers/i2c/busses/i2c-nomadik.c
+++ b/drivers/i2c/busses/i2c-nomadik.c
@@ -6,10 +6,10 @@
  * I2C master mode controller driver, used in Nomadik 8815
  * and Ux500 platforms.
  *
- * The Mobileye EyeQ5 platform is also supported; it uses
+ * The Mobileye EyeQ5 and EyeQ6H platforms are also supported; they use
  * the same Ux500/DB8500 IP block with two quirks:
  *  - The memory bus only supports 32-bit accesses.
- *  - A register must be configured for the I2C speed mode;
+ *  - (only EyeQ5) A register must be configured for the I2C speed mode;
  *    it is located in a shared register region called OLB.
  *
  * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
@@ -1046,8 +1046,6 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
 	struct regmap *olb;
 	unsigned int id;
 
-	priv->has_32b_bus = true;
-
 	olb = syscon_regmap_lookup_by_phandle_args(np, "mobileye,olb", 1, &id);
 	if (IS_ERR(olb))
 		return PTR_ERR(olb);
@@ -1070,13 +1068,15 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
 
 static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
 {
-	int ret = 0;
-	struct nmk_i2c_dev *priv;
-	struct device_node *np = adev->dev.of_node;
-	struct device *dev = &adev->dev;
-	struct i2c_adapter *adap;
 	struct i2c_vendor_data *vendor = id->data;
+	struct device_node *np = adev->dev.of_node;
+	bool is_eyeq6h = of_device_is_compatible(np, "mobileye,eyeq6h-i2c");
+	bool is_eyeq5 = of_device_is_compatible(np, "mobileye,eyeq5-i2c");
 	u32 max_fifo_threshold = (vendor->fifodepth / 2) - 1;
+	struct device *dev = &adev->dev;
+	struct nmk_i2c_dev *priv;
+	struct i2c_adapter *adap;
+	int ret = 0;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
@@ -1084,10 +1084,10 @@ static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
 
 	priv->vendor = vendor;
 	priv->adev = adev;
-	priv->has_32b_bus = false;
+	priv->has_32b_bus = is_eyeq5 || is_eyeq6h;
 	nmk_i2c_of_probe(np, priv);
 
-	if (of_device_is_compatible(np, "mobileye,eyeq5-i2c")) {
+	if (is_eyeq5) {
 		ret = nmk_i2c_eyeq5_probe(priv);
 		if (ret)
 			return dev_err_probe(dev, ret, "failed OLB lookup\n");

-- 
2.46.2

On Tue, Oct 08, 2024 at 12:29:41PM +0200, Théo Lebrun wrote:
> Add EyeQ6H support to the nmk-i2c AMBA driver. It shares the same quirk
> as EyeQ5: the memory bus only supports 32-bit accesses. Avoid writeb()
> and readb() by reusing the same `priv->has_32b_bus` flag.
> 
> It does NOT need to write speed-mode specific value into a register;
> therefore it does not depend on the mobileye,olb DT property.
> 
> Refactoring is done using is_eyeq5 and is_eyeq6h boolean local
> variables. Sort variables in reverse christmas tree to try and
> introduce some logic into the ordering.
> 
> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> ---
>  drivers/i2c/busses/i2c-nomadik.c | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
> index ad0f02acdb1215a1c04729f97bb14a4d93f88456..ea511d3a58073eaedb63850026e05b59427a69c6 100644
> --- a/drivers/i2c/busses/i2c-nomadik.c
> +++ b/drivers/i2c/busses/i2c-nomadik.c
> @@ -6,10 +6,10 @@
>   * I2C master mode controller driver, used in Nomadik 8815
>   * and Ux500 platforms.
>   *
> - * The Mobileye EyeQ5 platform is also supported; it uses
> + * The Mobileye EyeQ5 and EyeQ6H platforms are also supported; they use
>   * the same Ux500/DB8500 IP block with two quirks:
>   *  - The memory bus only supports 32-bit accesses.
> - *  - A register must be configured for the I2C speed mode;
> + *  - (only EyeQ5) A register must be configured for the I2C speed mode;
>   *    it is located in a shared register region called OLB.
>   *
>   * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
> @@ -1046,8 +1046,6 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
>  	struct regmap *olb;
>  	unsigned int id;
>  
> -	priv->has_32b_bus = true;
> -
>  	olb = syscon_regmap_lookup_by_phandle_args(np, "mobileye,olb", 1, &id);
>  	if (IS_ERR(olb))
>  		return PTR_ERR(olb);
> @@ -1070,13 +1068,15 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
>  
>  static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
>  {
> -	int ret = 0;
> -	struct nmk_i2c_dev *priv;
> -	struct device_node *np = adev->dev.of_node;
> -	struct device *dev = &adev->dev;
> -	struct i2c_adapter *adap;
>  	struct i2c_vendor_data *vendor = id->data;
> +	struct device_node *np = adev->dev.of_node;
> +	bool is_eyeq6h = of_device_is_compatible(np, "mobileye,eyeq6h-i2c");
> +	bool is_eyeq5 = of_device_is_compatible(np, "mobileye,eyeq5-i2c");

You should use match data, not add compatibles in the middle of code.
That's preferred, scallable pattern. What you added here last time does
not scale and above change is a proof for that.

Best regards,
Krzysztof

Hello Krzysztof,

On Tue Oct 8, 2024 at 3:39 PM CEST, Krzysztof Kozlowski wrote:
> On Tue, Oct 08, 2024 at 12:29:41PM +0200, Théo Lebrun wrote:
> > Add EyeQ6H support to the nmk-i2c AMBA driver. It shares the same quirk
> > as EyeQ5: the memory bus only supports 32-bit accesses. Avoid writeb()
> > and readb() by reusing the same `priv->has_32b_bus` flag.
> > 
> > It does NOT need to write speed-mode specific value into a register;
> > therefore it does not depend on the mobileye,olb DT property.
> > 
> > Refactoring is done using is_eyeq5 and is_eyeq6h boolean local
> > variables. Sort variables in reverse christmas tree to try and
> > introduce some logic into the ordering.
> > 
> > Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> > ---
> >  drivers/i2c/busses/i2c-nomadik.c | 22 +++++++++++-----------
> >  1 file changed, 11 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
> > index ad0f02acdb1215a1c04729f97bb14a4d93f88456..ea511d3a58073eaedb63850026e05b59427a69c6 100644
> > --- a/drivers/i2c/busses/i2c-nomadik.c
> > +++ b/drivers/i2c/busses/i2c-nomadik.c
> > @@ -6,10 +6,10 @@
> >   * I2C master mode controller driver, used in Nomadik 8815
> >   * and Ux500 platforms.
> >   *
> > - * The Mobileye EyeQ5 platform is also supported; it uses
> > + * The Mobileye EyeQ5 and EyeQ6H platforms are also supported; they use
> >   * the same Ux500/DB8500 IP block with two quirks:
> >   *  - The memory bus only supports 32-bit accesses.
> > - *  - A register must be configured for the I2C speed mode;
> > + *  - (only EyeQ5) A register must be configured for the I2C speed mode;
> >   *    it is located in a shared register region called OLB.
> >   *
> >   * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
> > @@ -1046,8 +1046,6 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
> >  	struct regmap *olb;
> >  	unsigned int id;
> >  
> > -	priv->has_32b_bus = true;
> > -
> >  	olb = syscon_regmap_lookup_by_phandle_args(np, "mobileye,olb", 1, &id);
> >  	if (IS_ERR(olb))
> >  		return PTR_ERR(olb);
> > @@ -1070,13 +1068,15 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
> >  
> >  static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
> >  {
> > -	int ret = 0;
> > -	struct nmk_i2c_dev *priv;
> > -	struct device_node *np = adev->dev.of_node;
> > -	struct device *dev = &adev->dev;
> > -	struct i2c_adapter *adap;
> >  	struct i2c_vendor_data *vendor = id->data;
> > +	struct device_node *np = adev->dev.of_node;
> > +	bool is_eyeq6h = of_device_is_compatible(np, "mobileye,eyeq6h-i2c");
> > +	bool is_eyeq5 = of_device_is_compatible(np, "mobileye,eyeq5-i2c");
>
> You should use match data, not add compatibles in the middle of code.
> That's preferred, scallable pattern. What you added here last time does
> not scale and above change is a proof for that.

I would have used match data if the driver struct had a .of_match_table
field. `struct amba_driver` does not. Are you recommending the approach
below?

I don't see how it brings much to the driver but I do get the scaling
issue as the number of support compatibles increases. This is a fear
based on what *could* happen in the future though.

------------------------------------------------------------------------

diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
index 82571983bbca..98fc40dfcbfc 100644
--- a/drivers/i2c/busses/i2c-nomadik.c
+++ b/drivers/i2c/busses/i2c-nomadik.c
@@ -26,6 +26,7 @@
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
@@ -1061,28 +1062,46 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
 	return 0;
 }

+#define NMK_I2C_EYEQ_FLAG_32B_BUS	BIT(0)
+#define NMK_I2C_EYEQ_FLAG_IS_EYEQ5	BIT(1)
+
+static const struct of_device_id nmk_i2c_eyeq_match_table[] = {
+	{
+		.compatible = "mobileye,eyeq5-i2c",
+		.data = (void*)(NMK_I2C_EYEQ_FLAG_32B_BUS | NMK_I2C_EYEQ_FLAG_IS_EYEQ5),
+	},
+	{
+		.compatible = "mobileye,eyeq6h-i2c",
+		.data = (void*)(NMK_I2C_EYEQ_FLAG_32B_BUS),
+	},
+};
+
 static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
 {
 	struct i2c_vendor_data *vendor = id->data;
 	struct device_node *np = adev->dev.of_node;
-	bool is_eyeq6h = of_device_is_compatible(np, "mobileye,eyeq6h-i2c");
-	bool is_eyeq5 = of_device_is_compatible(np, "mobileye,eyeq5-i2c");
 	u32 max_fifo_threshold = (vendor->fifodepth / 2) - 1;
+	const struct of_device_id *match;
 	struct device *dev = &adev->dev;
+	unsigned long match_flags = 0;
 	struct nmk_i2c_dev *priv;
 	struct i2c_adapter *adap;
 	int ret = 0;

+	match = of_match_device(nmk_i2c_eyeq_match_table, dev);
+	if (match)
+		match_flags = (unsigned long)match->data;
+
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	priv->vendor = vendor;
 	priv->adev = adev;
-	priv->has_32b_bus = is_eyeq5 || is_eyeq6h;
+	priv->has_32b_bus = match_flags & NMK_I2C_EYEQ_FLAG_32B_BUS;
 	nmk_i2c_of_probe(np, priv);

-	if (is_eyeq5) {
+	if (match_flags & NMK_I2C_EYEQ_FLAG_IS_EYEQ5) {
 		ret = nmk_i2c_eyeq5_probe(priv);
 		if (ret)
 			return dev_err_probe(dev, ret, "failed OLB lookup\n");

------------------------------------------------------------------------

Thanks Krzysztof,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

On 08/10/2024 16:43, Théo Lebrun wrote:
> Hello Krzysztof,
> 
> On Tue Oct 8, 2024 at 3:39 PM CEST, Krzysztof Kozlowski wrote:
>> On Tue, Oct 08, 2024 at 12:29:41PM +0200, Théo Lebrun wrote:
>>> Add EyeQ6H support to the nmk-i2c AMBA driver. It shares the same quirk
>>> as EyeQ5: the memory bus only supports 32-bit accesses. Avoid writeb()
>>> and readb() by reusing the same `priv->has_32b_bus` flag.
>>>
>>> It does NOT need to write speed-mode specific value into a register;
>>> therefore it does not depend on the mobileye,olb DT property.
>>>
>>> Refactoring is done using is_eyeq5 and is_eyeq6h boolean local
>>> variables. Sort variables in reverse christmas tree to try and
>>> introduce some logic into the ordering.
>>>
>>> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
>>> ---
>>>  drivers/i2c/busses/i2c-nomadik.c | 22 +++++++++++-----------
>>>  1 file changed, 11 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
>>> index ad0f02acdb1215a1c04729f97bb14a4d93f88456..ea511d3a58073eaedb63850026e05b59427a69c6 100644
>>> --- a/drivers/i2c/busses/i2c-nomadik.c
>>> +++ b/drivers/i2c/busses/i2c-nomadik.c
>>> @@ -6,10 +6,10 @@
>>>   * I2C master mode controller driver, used in Nomadik 8815
>>>   * and Ux500 platforms.
>>>   *
>>> - * The Mobileye EyeQ5 platform is also supported; it uses
>>> + * The Mobileye EyeQ5 and EyeQ6H platforms are also supported; they use
>>>   * the same Ux500/DB8500 IP block with two quirks:
>>>   *  - The memory bus only supports 32-bit accesses.
>>> - *  - A register must be configured for the I2C speed mode;
>>> + *  - (only EyeQ5) A register must be configured for the I2C speed mode;
>>>   *    it is located in a shared register region called OLB.
>>>   *
>>>   * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
>>> @@ -1046,8 +1046,6 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
>>>  	struct regmap *olb;
>>>  	unsigned int id;
>>>  
>>> -	priv->has_32b_bus = true;
>>> -
>>>  	olb = syscon_regmap_lookup_by_phandle_args(np, "mobileye,olb", 1, &id);
>>>  	if (IS_ERR(olb))
>>>  		return PTR_ERR(olb);
>>> @@ -1070,13 +1068,15 @@ static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
>>>  
>>>  static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
>>>  {
>>> -	int ret = 0;
>>> -	struct nmk_i2c_dev *priv;
>>> -	struct device_node *np = adev->dev.of_node;
>>> -	struct device *dev = &adev->dev;
>>> -	struct i2c_adapter *adap;
>>>  	struct i2c_vendor_data *vendor = id->data;
>>> +	struct device_node *np = adev->dev.of_node;
>>> +	bool is_eyeq6h = of_device_is_compatible(np, "mobileye,eyeq6h-i2c");
>>> +	bool is_eyeq5 = of_device_is_compatible(np, "mobileye,eyeq5-i2c");
>>
>> You should use match data, not add compatibles in the middle of code.
>> That's preferred, scallable pattern. What you added here last time does
>> not scale and above change is a proof for that.
> 
> I would have used match data if the driver struct had a .of_match_table
> field. `struct amba_driver` does not. Are you recommending the approach
> below?
> 
> I don't see how it brings much to the driver but I do get the scaling
> issue as the number of support compatibles increases. This is a fear
> based on what *could* happen in the future though.

You still have adev->dev.of_node, which you can use for matching in
probe. See for example of_match_device() (and add a note so people will
not convert it to device_get_match_data() blindly).

Best regards,
Krzysztof

On Tue Oct 8, 2024 at 6:03 PM CEST, Krzysztof Kozlowski wrote:
> On 08/10/2024 16:43, Théo Lebrun wrote:
> > On Tue Oct 8, 2024 at 3:39 PM CEST, Krzysztof Kozlowski wrote:
> >> On Tue, Oct 08, 2024 at 12:29:41PM +0200, Théo Lebrun wrote:
> >>> +	bool is_eyeq6h = of_device_is_compatible(np, "mobileye,eyeq6h-i2c");
> >>> +	bool is_eyeq5 = of_device_is_compatible(np, "mobileye,eyeq5-i2c");
> >>
> >> You should use match data, not add compatibles in the middle of code.
> >> That's preferred, scallable pattern. What you added here last time does
> >> not scale and above change is a proof for that.
> > 
> > I would have used match data if the driver struct had a .of_match_table
> > field. `struct amba_driver` does not. Are you recommending the approach
> > below?
> > 
> > I don't see how it brings much to the driver but I do get the scaling
> > issue as the number of support compatibles increases. This is a fear
> > based on what *could* happen in the future though.
>
> You still have adev->dev.of_node, which you can use for matching in
> probe. See for example of_match_device() (and add a note so people will
> not convert it to device_get_match_data() blindly).

Just sent the new revision [0]. It uses of_match_device() in the same
way as was shown in my previous answer to this thread [1]. Followed
your recommendation and added a comment to avoid conversions to
device_get_match_data().

Thanks!

[0]: https://lore.kernel.org/lkml/20241009-mbly-i2c-v2-0-ac9230a8dac5@bootlin.com/
[1]: https://lore.kernel.org/lkml/D4QI63B6YQU5.3UPKA7G75J445@bootlin.com/

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com