diff mbox series

[v3,5/5] i2c: muxes: pca954x: Allow sharing reset GPIO

Message ID 20240112163608.528453-6-krzysztof.kozlowski@linaro.org
State New
Headers show
Series reset: gpio: ASoC: shared GPIO resets | expand

Commit Message

Krzysztof Kozlowski Jan. 12, 2024, 4:36 p.m. UTC 
From: Chris Packham <chris.packham@alliedtelesis.co.nz>

Some hardware designs with multiple PCA954x devices use a reset GPIO
connected to all the muxes. Support this configuration by making use of
the reset controller framework which can deal with the shared reset
GPIOs. Fall back to the old GPIO descriptor method if the reset
controller framework is not enabled.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Acked-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240108041913.7078-1-chris.packham@alliedtelesis.co.nz
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

---

If previous patches are fine, then this commit is independent and could
be taken via I2C.

Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Sean Anderson <sean.anderson@seco.com>
---
 drivers/i2c/muxes/i2c-mux-pca954x.c | 46 ++++++++++++++++++++++++-----
 1 file changed, 38 insertions(+), 8 deletions(-)

Comments

Philipp Zabel Jan. 16, 2024, 3:18 p.m. UTC | #1 
On Fr, 2024-01-12 at 17:36 +0100, Krzysztof Kozlowski wrote:
> From: Chris Packham <chris.packham@alliedtelesis.co.nz>
> 
> Some hardware designs with multiple PCA954x devices use a reset GPIO
> connected to all the muxes. Support this configuration by making use of
> the reset controller framework which can deal with the shared reset
> GPIOs. Fall back to the old GPIO descriptor method if the reset
> controller framework is not enabled.
> 
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> Acked-by: Peter Rosin <peda@axentia.se>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Link: https://lore.kernel.org/r/20240108041913.7078-1-chris.packham@alliedtelesis.co.nz
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 
> ---
> 
> If previous patches are fine, then this commit is independent and could
> be taken via I2C.
> 
> Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
> Cc: Bartosz Golaszewski <brgl@bgdev.pl>
> Cc: Sean Anderson <sean.anderson@seco.com>
> ---
>  drivers/i2c/muxes/i2c-mux-pca954x.c | 46 ++++++++++++++++++++++++-----
>  1 file changed, 38 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
> index 2219062104fb..1702e8d49b91 100644
> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> @@ -49,6 +49,7 @@
>  #include <linux/pm.h>
>  #include <linux/property.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/reset.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
>  #include <dt-bindings/mux/mux.h>
> @@ -102,6 +103,9 @@ struct pca954x {
>  	unsigned int irq_mask;
>  	raw_spinlock_t lock;
>  	struct regulator *supply;
> +
> +	struct gpio_desc *reset_gpio;
> +	struct reset_control *reset_cont;
>  };
>  
>  /* Provide specs for the MAX735x, PCA954x and PCA984x types we know about */
> @@ -477,6 +481,35 @@ static int pca954x_init(struct i2c_client *client, struct pca954x *data)
>  	return ret;
>  }
>  
> +static int pca954x_get_reset(struct device *dev, struct pca954x *data)
> +{
> +	data->reset_cont = devm_reset_control_get_optional_shared(dev, NULL);
> +	if (IS_ERR(data->reset_cont))
> +		return dev_err_probe(dev, PTR_ERR(data->reset_cont),
> +				     "Failed to get reset\n");
> +	else if (data->reset_cont)
> +		return 0;
> +
> +	/*
> +	 * fallback to legacy reset-gpios
> +	 */

devm_reset_control_get_optional_shared() won't return NULL if the
"reset-gpios" property is found in the device tree, so the GPIO
fallback is dead code.

> +	data->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(data->reset_gpio)) {
> +		return dev_err_probe(dev, PTR_ERR(data->reset_gpio),
> +				     "Failed to get reset gpio");
> +	}
> +
> +	return 0;
> +}
> +

regards
Philipp
Chris Packham Jan. 16, 2024, 7:58 p.m. UTC | #2 
On 17/01/24 04:18, Philipp Zabel wrote:
> On Fr, 2024-01-12 at 17:36 +0100, Krzysztof Kozlowski wrote:
>> From: Chris Packham <chris.packham@alliedtelesis.co.nz>
>>
>> Some hardware designs with multiple PCA954x devices use a reset GPIO
>> connected to all the muxes. Support this configuration by making use of
>> the reset controller framework which can deal with the shared reset
>> GPIOs. Fall back to the old GPIO descriptor method if the reset
>> controller framework is not enabled.
>>
>> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
>> Acked-by: Peter Rosin <peda@axentia.se>
>> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> Link: https://scanmail.trustwave.com/?c=20988&d=8p6m5Tfi2yYJWYV9xYGcYnz7UYxB6WTGTPkmGu7b8A&u=https%3a%2f%2flore%2ekernel%2eorg%2fr%2f20240108041913%2e7078-1-chris%2epackham%40alliedtelesis%2eco%2enz
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>
>> ---
>>
>> If previous patches are fine, then this commit is independent and could
>> be taken via I2C.
>>
>> Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
>> Cc: Bartosz Golaszewski <brgl@bgdev.pl>
>> Cc: Sean Anderson <sean.anderson@seco.com>
>> ---
>>   drivers/i2c/muxes/i2c-mux-pca954x.c | 46 ++++++++++++++++++++++++-----
>>   1 file changed, 38 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
>> index 2219062104fb..1702e8d49b91 100644
>> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
>> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
>> @@ -49,6 +49,7 @@
>>   #include <linux/pm.h>
>>   #include <linux/property.h>
>>   #include <linux/regulator/consumer.h>
>> +#include <linux/reset.h>
>>   #include <linux/slab.h>
>>   #include <linux/spinlock.h>
>>   #include <dt-bindings/mux/mux.h>
>> @@ -102,6 +103,9 @@ struct pca954x {
>>   	unsigned int irq_mask;
>>   	raw_spinlock_t lock;
>>   	struct regulator *supply;
>> +
>> +	struct gpio_desc *reset_gpio;
>> +	struct reset_control *reset_cont;
>>   };
>>   
>>   /* Provide specs for the MAX735x, PCA954x and PCA984x types we know about */
>> @@ -477,6 +481,35 @@ static int pca954x_init(struct i2c_client *client, struct pca954x *data)
>>   	return ret;
>>   }
>>   
>> +static int pca954x_get_reset(struct device *dev, struct pca954x *data)
>> +{
>> +	data->reset_cont = devm_reset_control_get_optional_shared(dev, NULL);
>> +	if (IS_ERR(data->reset_cont))
>> +		return dev_err_probe(dev, PTR_ERR(data->reset_cont),
>> +				     "Failed to get reset\n");
>> +	else if (data->reset_cont)
>> +		return 0;
>> +
>> +	/*
>> +	 * fallback to legacy reset-gpios
>> +	 */
> devm_reset_control_get_optional_shared() won't return NULL if the
> "reset-gpios" property is found in the device tree, so the GPIO
> fallback is dead code.

Hmm, I was attempting to handle the case where CONFIG_RESET_GPIO wasn't 
set or the reset core wasn't enabled. It doesn't appear that the latter 
is even possible so no need to worry about that. For the former it looks 
like we'd get -EPROBE_DEFER. I could change to check for that or just 
remove the GPIO fallback entirely. Any preference?

>
>> +	data->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>> +	if (IS_ERR(data->reset_gpio)) {
>> +		return dev_err_probe(dev, PTR_ERR(data->reset_gpio),
>> +				     "Failed to get reset gpio");
>> +	}
>> +
>> +	return 0;
>> +}
>> +
> regards
> Philipp
Philipp Zabel Jan. 17, 2024, 11:16 a.m. UTC | #3 
On Di, 2024-01-16 at 19:58 +0000, Chris Packham wrote:
> On 17/01/24 04:18, Philipp Zabel wrote:
> > On Fr, 2024-01-12 at 17:36 +0100, Krzysztof Kozlowski wrote:
> > > From: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > > 
> > > Some hardware designs with multiple PCA954x devices use a reset GPIO
> > > connected to all the muxes. Support this configuration by making use of
> > > the reset controller framework which can deal with the shared reset
> > > GPIOs. Fall back to the old GPIO descriptor method if the reset
> > > controller framework is not enabled.
> > > 
> > > Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > > Acked-by: Peter Rosin <peda@axentia.se>
> > > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> > > Link: https://scanmail.trustwave.com/?c=20988&d=8p6m5Tfi2yYJWYV9xYGcYnz7UYxB6WTGTPkmGu7b8A&u=https%3a%2f%2flore%2ekernel%2eorg%2fr%2f20240108041913%2e7078-1-chris%2epackham%40alliedtelesis%2eco%2enz
> > > Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> > > 
> > > ---
> > > 
> > > If previous patches are fine, then this commit is independent and could
> > > be taken via I2C.
> > > 
> > > Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > > Cc: Bartosz Golaszewski <brgl@bgdev.pl>
> > > Cc: Sean Anderson <sean.anderson@seco.com>
> > > ---
> > >   drivers/i2c/muxes/i2c-mux-pca954x.c | 46 ++++++++++++++++++++++++-----
> > >   1 file changed, 38 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
> > > index 2219062104fb..1702e8d49b91 100644
> > > --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> > > +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> > > @@ -49,6 +49,7 @@
> > >   #include <linux/pm.h>
> > >   #include <linux/property.h>
> > >   #include <linux/regulator/consumer.h>
> > > +#include <linux/reset.h>
> > >   #include <linux/slab.h>
> > >   #include <linux/spinlock.h>
> > >   #include <dt-bindings/mux/mux.h>
> > > @@ -102,6 +103,9 @@ struct pca954x {
> > >   	unsigned int irq_mask;
> > >   	raw_spinlock_t lock;
> > >   	struct regulator *supply;
> > > +
> > > +	struct gpio_desc *reset_gpio;
> > > +	struct reset_control *reset_cont;
> > >   };
> > >   
> > >   /* Provide specs for the MAX735x, PCA954x and PCA984x types we know about */
> > > @@ -477,6 +481,35 @@ static int pca954x_init(struct i2c_client *client, struct pca954x *data)
> > >   	return ret;
> > >   }
> > >   
> > > +static int pca954x_get_reset(struct device *dev, struct pca954x *data)
> > > +{
> > > +	data->reset_cont = devm_reset_control_get_optional_shared(dev, NULL);
> > > +	if (IS_ERR(data->reset_cont))
> > > +		return dev_err_probe(dev, PTR_ERR(data->reset_cont),
> > > +				     "Failed to get reset\n");
> > > +	else if (data->reset_cont)
> > > +		return 0;
> > > +
> > > +	/*
> > > +	 * fallback to legacy reset-gpios
> > > +	 */
> > devm_reset_control_get_optional_shared() won't return NULL if the
> > "reset-gpios" property is found in the device tree, so the GPIO
> > fallback is dead code.
> 
> Hmm, I was attempting to handle the case where CONFIG_RESET_GPIO wasn't 
> set [...]
> [...] it looks like we'd get -EPROBE_DEFER. I could change to check
> for that or just remove the GPIO fallback entirely. Any preference?

I hadn't considered this.

If CONFIG_RESET_GPIO=n, devm_reset_control_get_optional_shared()
probably shouldn't return -EPROBE_DEFER. If we change that, the GPIO
fallback here can stay as is.

The alternative would be to drop the fallback and select RESET_GPIO.
Using -EPROBE_DEFER for fallback detection is no good, as there could
be a valid probe deferral if reset-gpio is compiled as a module that
will be loaded later.

regards
Philipp
Chris Packham Jan. 17, 2024, 7:56 p.m. UTC | #4 
On 18/01/24 00:16, Philipp Zabel wrote:
> On Di, 2024-01-16 at 19:58 +0000, Chris Packham wrote:
>> On 17/01/24 04:18, Philipp Zabel wrote:
>>> On Fr, 2024-01-12 at 17:36 +0100, Krzysztof Kozlowski wrote:
>>>> From: Chris Packham <chris.packham@alliedtelesis.co.nz>
>>>>
>>>> Some hardware designs with multiple PCA954x devices use a reset GPIO
>>>> connected to all the muxes. Support this configuration by making use of
>>>> the reset controller framework which can deal with the shared reset
>>>> GPIOs. Fall back to the old GPIO descriptor method if the reset
>>>> controller framework is not enabled.
>>>>
>>>> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
>>>> Acked-by: Peter Rosin <peda@axentia.se>
>>>> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>> Link: https://scanmail.trustwave.com/?c=20988&d=_ban5W3xRzKSimJ9ijTJ74p10otfq8ZONfjVnBr6Fw&u=https%3a%2f%2flore%2ekernel%2eorg%2fr%2f20240108041913%2e7078-1-chris%2epackham%40alliedtelesis%2eco%2enz
>>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>>
>>>> ---
>>>>
>>>> If previous patches are fine, then this commit is independent and could
>>>> be taken via I2C.
>>>>
>>>> Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
>>>> Cc: Bartosz Golaszewski <brgl@bgdev.pl>
>>>> Cc: Sean Anderson <sean.anderson@seco.com>
>>>> ---
>>>>    drivers/i2c/muxes/i2c-mux-pca954x.c | 46 ++++++++++++++++++++++++-----
>>>>    1 file changed, 38 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
>>>> index 2219062104fb..1702e8d49b91 100644
>>>> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
>>>> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
>>>> @@ -49,6 +49,7 @@
>>>>    #include <linux/pm.h>
>>>>    #include <linux/property.h>
>>>>    #include <linux/regulator/consumer.h>
>>>> +#include <linux/reset.h>
>>>>    #include <linux/slab.h>
>>>>    #include <linux/spinlock.h>
>>>>    #include <dt-bindings/mux/mux.h>
>>>> @@ -102,6 +103,9 @@ struct pca954x {
>>>>    	unsigned int irq_mask;
>>>>    	raw_spinlock_t lock;
>>>>    	struct regulator *supply;
>>>> +
>>>> +	struct gpio_desc *reset_gpio;
>>>> +	struct reset_control *reset_cont;
>>>>    };
>>>>    
>>>>    /* Provide specs for the MAX735x, PCA954x and PCA984x types we know about */
>>>> @@ -477,6 +481,35 @@ static int pca954x_init(struct i2c_client *client, struct pca954x *data)
>>>>    	return ret;
>>>>    }
>>>>    
>>>> +static int pca954x_get_reset(struct device *dev, struct pca954x *data)
>>>> +{
>>>> +	data->reset_cont = devm_reset_control_get_optional_shared(dev, NULL);
>>>> +	if (IS_ERR(data->reset_cont))
>>>> +		return dev_err_probe(dev, PTR_ERR(data->reset_cont),
>>>> +				     "Failed to get reset\n");
>>>> +	else if (data->reset_cont)
>>>> +		return 0;
>>>> +
>>>> +	/*
>>>> +	 * fallback to legacy reset-gpios
>>>> +	 */
>>> devm_reset_control_get_optional_shared() won't return NULL if the
>>> "reset-gpios" property is found in the device tree, so the GPIO
>>> fallback is dead code.
>> Hmm, I was attempting to handle the case where CONFIG_RESET_GPIO wasn't
>> set [...]
>> [...] it looks like we'd get -EPROBE_DEFER. I could change to check
>> for that or just remove the GPIO fallback entirely. Any preference?
> I hadn't considered this.
>
> If CONFIG_RESET_GPIO=n, devm_reset_control_get_optional_shared()
> probably shouldn't return -EPROBE_DEFER. If we change that, the GPIO
> fallback here can stay as is.
>
> The alternative would be to drop the fallback and select RESET_GPIO.
> Using -EPROBE_DEFER for fallback detection is no good, as there could
> be a valid probe deferral if reset-gpio is compiled as a module that
> will be loaded later.
I did consider adding `select RESET_GPIO` (or maybe just `imply 
RESET_GPIO`) initially but decided on the fallback as a way of avoiding 
surprises for existing users. I'll see if anyone else has a different 
suggestion but assuming nothing else changes I'll work with Krzystof to 
get an updated patch for this series.
diff mbox series

Patch

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index 2219062104fb..1702e8d49b91 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -49,6 +49,7 @@ 
 #include <linux/pm.h>
 #include <linux/property.h>
 #include <linux/regulator/consumer.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <dt-bindings/mux/mux.h>
@@ -102,6 +103,9 @@  struct pca954x {
 	unsigned int irq_mask;
 	raw_spinlock_t lock;
 	struct regulator *supply;
+
+	struct gpio_desc *reset_gpio;
+	struct reset_control *reset_cont;
 };
 
 /* Provide specs for the MAX735x, PCA954x and PCA984x types we know about */
@@ -477,6 +481,35 @@  static int pca954x_init(struct i2c_client *client, struct pca954x *data)
 	return ret;
 }
 
+static int pca954x_get_reset(struct device *dev, struct pca954x *data)
+{
+	data->reset_cont = devm_reset_control_get_optional_shared(dev, NULL);
+	if (IS_ERR(data->reset_cont))
+		return dev_err_probe(dev, PTR_ERR(data->reset_cont),
+				     "Failed to get reset\n");
+	else if (data->reset_cont)
+		return 0;
+
+	/*
+	 * fallback to legacy reset-gpios
+	 */
+	data->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(data->reset_gpio)) {
+		return dev_err_probe(dev, PTR_ERR(data->reset_gpio),
+				     "Failed to get reset gpio");
+	}
+
+	return 0;
+}
+
+static void pca954x_reset_deassert(struct pca954x *data)
+{
+	if (data->reset_cont)
+		reset_control_deassert(data->reset_cont);
+	else
+		gpiod_set_value_cansleep(data->reset_gpio, 0);
+}
+
 /*
  * I2C init/probing/exit functions
  */
@@ -485,7 +518,6 @@  static int pca954x_probe(struct i2c_client *client)
 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
 	struct i2c_adapter *adap = client->adapter;
 	struct device *dev = &client->dev;
-	struct gpio_desc *gpio;
 	struct i2c_mux_core *muxc;
 	struct pca954x *data;
 	int num;
@@ -513,15 +545,13 @@  static int pca954x_probe(struct i2c_client *client)
 		return dev_err_probe(dev, ret,
 				     "Failed to enable vdd supply\n");
 
-	/* Reset the mux if a reset GPIO is specified. */
-	gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
-	if (IS_ERR(gpio)) {
-		ret = PTR_ERR(gpio);
+	ret = pca954x_get_reset(dev, data);
+	if (ret)
 		goto fail_cleanup;
-	}
-	if (gpio) {
+
+	if (data->reset_cont || data->reset_gpio) {
 		udelay(1);
-		gpiod_set_value_cansleep(gpio, 0);
+		pca954x_reset_deassert(data);
 		/* Give the chip some time to recover. */
 		udelay(1);
 	}