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Subject[PATCH v2 1/1] gpio: mvebu: Add support for multiple PWM lines per GPIO chip
Date
Allow more than 1 PWM request (eg. PWM fan) on the same GPIO chip. If
the other PWM counter is unused, allocate it to next PWM request.
The priority would be:
1. Default counter assigned to the bank
2. Unused counter that is assigned to other bank

Since there are only two PWM counters, only two PWMs supported.

Signed-off-by: Aditya Prayoga <aditya@kobol.io>
---
drivers/gpio/gpio-mvebu.c | 73 ++++++++++++++++++++++++++++++++++++++---------
1 file changed, 60 insertions(+), 13 deletions(-)

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 6e02148..2d46b87 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -92,9 +92,16 @@

#define MVEBU_MAX_GPIO_PER_BANK 32

+enum mvebu_pwm_counter {
+ MVEBU_PWM_CTRL_SET_A = 0,
+ MVEBU_PWM_CTRL_SET_B,
+ MVEBU_PWM_CTRL_MAX
+};
+
struct mvebu_pwm {
void __iomem *membase;
unsigned long clk_rate;
+ enum mvebu_pwm_counter id;
struct gpio_desc *gpiod;
struct pwm_chip chip;
spinlock_t lock;
@@ -128,6 +135,8 @@ struct mvebu_gpio_chip {
u32 level_mask_regs[4];
};

+static struct mvebu_pwm *mvebu_pwm_list[MVEBU_PWM_CTRL_MAX];
+
/*
* Functions returning addresses of individual registers for a given
* GPIO controller.
@@ -594,34 +603,59 @@ static struct mvebu_pwm *to_mvebu_pwm(struct pwm_chip *chip)
return container_of(chip, struct mvebu_pwm, chip);
}

+static struct mvebu_pwm *mvebu_pwm_get_avail_counter(void)
+{
+ enum mvebu_pwm_counter i;
+
+ for (i = MVEBU_PWM_CTRL_SET_A; i < MVEBU_PWM_CTRL_MAX; i++) {
+ if (!mvebu_pwm_list[i]->gpiod)
+ return mvebu_pwm_list[i];
+ }
+ return NULL;
+}
+
static int mvebu_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct mvebu_pwm *mvpwm = to_mvebu_pwm(chip);
struct mvebu_gpio_chip *mvchip = mvpwm->mvchip;
struct gpio_desc *desc;
+ struct mvebu_pwm *counter;
unsigned long flags;
int ret = 0;

spin_lock_irqsave(&mvpwm->lock, flags);

- if (mvpwm->gpiod) {
- ret = -EBUSY;
- } else {
- desc = gpiochip_request_own_desc(&mvchip->chip,
- pwm->hwpwm, "mvebu-pwm");
- if (IS_ERR(desc)) {
- ret = PTR_ERR(desc);
+ counter = mvpwm;
+ if (counter->gpiod) {
+ counter = mvebu_pwm_get_avail_counter();
+ if (!counter) {
+ ret = -EBUSY;
goto out;
}

- ret = gpiod_direction_output(desc, 0);
- if (ret) {
- gpiochip_free_own_desc(desc);
- goto out;
- }
+ pwm->chip_data = counter;
+ }

- mvpwm->gpiod = desc;
+ desc = gpiochip_request_own_desc(&mvchip->chip,
+ pwm->hwpwm, "mvebu-pwm");
+ if (IS_ERR(desc)) {
+ ret = PTR_ERR(desc);
+ goto out;
}
+
+ ret = gpiod_direction_output(desc, 0);
+ if (ret) {
+ gpiochip_free_own_desc(desc);
+ goto out;
+ }
+
+ regmap_update_bits(mvchip->regs, GPIO_BLINK_CNT_SELECT_OFF +
+ mvchip->offset, BIT(pwm->hwpwm),
+ counter->id ? BIT(pwm->hwpwm) : 0);
+ regmap_read(mvchip->regs, GPIO_BLINK_CNT_SELECT_OFF +
+ mvchip->offset, &counter->blink_select);
+
+ counter->gpiod = desc;
out:
spin_unlock_irqrestore(&mvpwm->lock, flags);
return ret;
@@ -632,6 +666,11 @@ static void mvebu_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
struct mvebu_pwm *mvpwm = to_mvebu_pwm(chip);
unsigned long flags;

+ if (pwm->chip_data) {
+ mvpwm = (struct mvebu_pwm *) pwm->chip_data;
+ pwm->chip_data = NULL;
+ }
+
spin_lock_irqsave(&mvpwm->lock, flags);
gpiochip_free_own_desc(mvpwm->gpiod);
mvpwm->gpiod = NULL;
@@ -648,6 +687,9 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
unsigned long flags;
u32 u;

+ if (pwm->chip_data)
+ mvpwm = (struct mvebu_pwm *) pwm->chip_data;
+
spin_lock_irqsave(&mvpwm->lock, flags);

val = (unsigned long long)
@@ -695,6 +737,9 @@ static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
unsigned long flags;
unsigned int on, off;

+ if (pwm->chip_data)
+ mvpwm = (struct mvebu_pwm *) pwm->chip_data;
+
val = (unsigned long long) mvpwm->clk_rate * state->duty_cycle;
do_div(val, NSEC_PER_SEC);
if (val > UINT_MAX)
@@ -804,6 +849,7 @@ static int mvebu_pwm_probe(struct platform_device *pdev,
return -ENOMEM;
mvchip->mvpwm = mvpwm;
mvpwm->mvchip = mvchip;
+ mvpwm->id = id;

mvpwm->membase = devm_ioremap_resource(dev, res);
if (IS_ERR(mvpwm->membase))
@@ -825,6 +871,7 @@ static int mvebu_pwm_probe(struct platform_device *pdev,
* region.
*/
mvpwm->chip.base = -1;
+ mvebu_pwm_list[id] = mvpwm;

spin_lock_init(&mvpwm->lock);

--
2.7.4
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