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[PATCH 12/13] pwm: jz4740: Let the pinctrl driver configure the pins

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  [PATCH 12/13] pwm: jz4740: Let the pinctrl driver configure the pins Paul Cercueil <paul@crapouillou.net> - 2017-01-18 00:20 +0100
    Re: [PATCH 12/13] pwm: jz4740: Let the pinctrl driver configure the  pins Thierry Reding <thierry.reding@gmail.com> - 2017-01-18 08:30 +0100

#1561089 — [PATCH 12/13] pwm: jz4740: Let the pinctrl driver configure the pins

Now that the JZ4740 and similar SoCs have a pinctrl driver, we rely on
the pins being properly configured before the driver probes.

One inherent problem of this new approach is that the pinctrl framework
does not allow us to configure each pin on demand, when the various PWM
channels are requested or released. For instance, the PWM channels can
be configured from sysfs, which would require all PWM pins to be configured
properly beforehand for the PWM function, eventually causing conflicts
with other platform or board drivers.

The proper solution here would be to modify the pwm-jz4740 driver to
handle only one PWM channel, and create an instance of this driver
for each one of the 8 PWM channels. Then, it could use the pinctrl
framework to dynamically configure the PWM pin it controls.

Until this can be done, the only jz4740 board supported upstream
(Qi lb60) could configure all of its connected PWM pins in PWM function
mode, if those are not used by other drivers nor by GPIOs on the
board.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/pwm/pwm-jz4740.c | 29 -----------------------------
 1 file changed, 29 deletions(-)

diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
index 76d13150283f..a75ff3622450 100644
--- a/drivers/pwm/pwm-jz4740.c
+++ b/drivers/pwm/pwm-jz4740.c
@@ -21,22 +21,10 @@
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 
-#include <asm/mach-jz4740/gpio.h>
 #include <asm/mach-jz4740/timer.h>
 
 #define NUM_PWM 8
 
-static const unsigned int jz4740_pwm_gpio_list[NUM_PWM] = {
-	JZ_GPIO_PWM0,
-	JZ_GPIO_PWM1,
-	JZ_GPIO_PWM2,
-	JZ_GPIO_PWM3,
-	JZ_GPIO_PWM4,
-	JZ_GPIO_PWM5,
-	JZ_GPIO_PWM6,
-	JZ_GPIO_PWM7,
-};
-
 struct jz4740_pwm_chip {
 	struct pwm_chip chip;
 	struct clk *clk;
@@ -49,9 +37,6 @@ static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
 
 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 {
-	unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm];
-	int ret;
-
 	/*
 	 * Timers 0 and 1 are used for system tasks, so they are unavailable
 	 * for use as PWMs.
@@ -59,15 +44,6 @@ static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 	if (pwm->hwpwm < 2)
 		return -EBUSY;
 
-	ret = gpio_request(gpio, pwm->label);
-	if (ret) {
-		dev_err(chip->dev, "Failed to request GPIO#%u for PWM: %d\n",
-			gpio, ret);
-		return ret;
-	}
-
-	jz_gpio_set_function(gpio, JZ_GPIO_FUNC_PWM);
-
 	jz4740_timer_start(pwm->hwpwm);
 
 	return 0;
@@ -75,13 +51,8 @@ static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 
 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
-	unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm];
-
 	jz4740_timer_set_ctrl(pwm->hwpwm, 0);
 
-	jz_gpio_set_function(gpio, JZ_GPIO_FUNC_NONE);
-	gpio_free(gpio);
-
 	jz4740_timer_stop(pwm->hwpwm);
 }
 
-- 
2.11.0

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#1561334 — Re: [PATCH 12/13] pwm: jz4740: Let the pinctrl driver configure the pins

[Multipart message — attachments visible in raw view] — view raw

On Wed, Jan 18, 2017 at 12:14:20AM +0100, Paul Cercueil wrote:
> Now that the JZ4740 and similar SoCs have a pinctrl driver, we rely on
> the pins being properly configured before the driver probes.
> 
> One inherent problem of this new approach is that the pinctrl framework
> does not allow us to configure each pin on demand, when the various PWM
> channels are requested or released. For instance, the PWM channels can
> be configured from sysfs, which would require all PWM pins to be configured
> properly beforehand for the PWM function, eventually causing conflicts
> with other platform or board drivers.
> 
> The proper solution here would be to modify the pwm-jz4740 driver to
> handle only one PWM channel, and create an instance of this driver
> for each one of the 8 PWM channels. Then, it could use the pinctrl
> framework to dynamically configure the PWM pin it controls.
> 
> Until this can be done, the only jz4740 board supported upstream
> (Qi lb60) could configure all of its connected PWM pins in PWM function
> mode, if those are not used by other drivers nor by GPIOs on the
> board.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/pwm/pwm-jz4740.c | 29 -----------------------------
>  1 file changed, 29 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
> index 76d13150283f..a75ff3622450 100644
> --- a/drivers/pwm/pwm-jz4740.c
> +++ b/drivers/pwm/pwm-jz4740.c
> @@ -21,22 +21,10 @@
>  #include <linux/platform_device.h>
>  #include <linux/pwm.h>
>  
> -#include <asm/mach-jz4740/gpio.h>

What about the linux/gpio.h header? It seems to me like that would be no
longer needed after this patch either.

Other than that this looks like the patch I'd expect if the pinmux was
configured statically, based on board design.

Thierry

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