pwm: Manage owner assignment implicitly for drivers

Instead of requiring each driver to care for assigning the owner member
of struct pwm_ops, handle that implicitly using a macro. Note that the
owner member has to be moved to struct pwm_chip, as the ops structure
usually lives in read-only memory and so cannot be modified.

The upside is that new low level drivers cannot forget the assignment and
save one line each. The pwm-crc driver didn't assign .owner, that's not
a problem in practice though as the driver cannot be compiled as a
module.

Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # Intel LPSS
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com> # pwm-{bcm,brcm}*.c
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com> # sun4i
Acked-by: Andi Shyti <andi.shyti@kernel.org>
Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> # pwm-visconti
Acked-by: Heiko Stuebner <heiko@sntech.de> # pwm-rockchip
Acked-by: Michael Walle <michael@walle.cc> # pwm-sl28cpld
Acked-by: Neil Armstrong <neil.armstrong@linaro.org> # pwm-meson
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230804142707.412137-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 14 insertions, 10 deletions

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index dc66e3405bf5..a2824eb4e236 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -89,13 +89,13 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
 	if (test_bit(PWMF_REQUESTED, &pwm->flags))
 		return -EBUSY;
 
-	if (!try_module_get(pwm->chip->ops->owner))
+	if (!try_module_get(pwm->chip->owner))
 		return -ENODEV;
 
 	if (pwm->chip->ops->request) {
 		err = pwm->chip->ops->request(pwm->chip, pwm);
 		if (err) {
-			module_put(pwm->chip->ops->owner);
+			module_put(pwm->chip->owner);
 			return err;
 		}
 	}
@@ -253,14 +253,16 @@ static bool pwm_ops_check(const struct pwm_chip *chip)
 }
 
 /**
- * pwmchip_add() - register a new PWM chip
+ * __pwmchip_add() - register a new PWM chip
  * @chip: the PWM chip to add
+ * @owner: reference to the module providing the chip.
  *
- * Register a new PWM chip.
+ * Register a new PWM chip. @owner is supposed to be THIS_MODULE, use the
+ * pwmchip_add wrapper to do this right.
  *
  * Returns: 0 on success or a negative error code on failure.
  */
-int pwmchip_add(struct pwm_chip *chip)
+int __pwmchip_add(struct pwm_chip *chip, struct module *owner)
 {
 	struct pwm_device *pwm;
 	unsigned int i;
@@ -272,6 +274,8 @@ int pwmchip_add(struct pwm_chip *chip)
 	if (!pwm_ops_check(chip))
 		return -EINVAL;
 
+	chip->owner = owner;
+
 	chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL);
 	if (!chip->pwms)
 		return -ENOMEM;
@@ -306,7 +310,7 @@ int pwmchip_add(struct pwm_chip *chip)
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(pwmchip_add);
+EXPORT_SYMBOL_GPL(__pwmchip_add);
 
 /**
  * pwmchip_remove() - remove a PWM chip
@@ -338,17 +342,17 @@ static void devm_pwmchip_remove(void *data)
 	pwmchip_remove(chip);
 }
 
-int devm_pwmchip_add(struct device *dev, struct pwm_chip *chip)
+int __devm_pwmchip_add(struct device *dev, struct pwm_chip *chip, struct module *owner)
 {
 	int ret;
 
-	ret = pwmchip_add(chip);
+	ret = __pwmchip_add(chip, owner);
 	if (ret)
 		return ret;
 
 	return devm_add_action_or_reset(dev, devm_pwmchip_remove, chip);
 }
-EXPORT_SYMBOL_GPL(devm_pwmchip_add);
+EXPORT_SYMBOL_GPL(__devm_pwmchip_add);
 
 /**
  * pwm_request_from_chip() - request a PWM device relative to a PWM chip
@@ -979,7 +983,7 @@ void pwm_put(struct pwm_device *pwm)
 	pwm_set_chip_data(pwm, NULL);
 	pwm->label = NULL;
 
-	module_put(pwm->chip->ops->owner);
+	module_put(pwm->chip->owner);
 out:
 	mutex_unlock(&pwm_lock);
 }