diff options
Diffstat (limited to 'drivers/pwm/pwm-lpss.c')
| -rw-r--r-- | drivers/pwm/pwm-lpss.c | 57 |
1 files changed, 40 insertions, 17 deletions
diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c index 25044104003b..295b963dbddb 100644 --- a/drivers/pwm/pwm-lpss.c +++ b/drivers/pwm/pwm-lpss.c @@ -13,10 +13,12 @@ * published by the Free Software Foundation. */ +#include <linux/delay.h> #include <linux/io.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/pm_runtime.h> +#include <linux/time.h> #include "pwm-lpss.h" @@ -24,11 +26,8 @@ #define PWM_ENABLE BIT(31) #define PWM_SW_UPDATE BIT(30) #define PWM_BASE_UNIT_SHIFT 8 -#define PWM_BASE_UNIT_MASK 0x00ffff00 #define PWM_ON_TIME_DIV_MASK 0x000000ff #define PWM_DIVISION_CORRECTION 0x2 -#define PWM_LIMIT (0x8000 + PWM_DIVISION_CORRECTION) -#define NSECS_PER_SEC 1000000000UL /* Size of each PWM register space if multiple */ #define PWM_SIZE 0x400 @@ -36,13 +35,14 @@ struct pwm_lpss_chip { struct pwm_chip chip; void __iomem *regs; - unsigned long clk_rate; + const struct pwm_lpss_boardinfo *info; }; /* BayTrail */ const struct pwm_lpss_boardinfo pwm_lpss_byt_info = { .clk_rate = 25000000, .npwm = 1, + .base_unit_bits = 16, }; EXPORT_SYMBOL_GPL(pwm_lpss_byt_info); @@ -50,6 +50,7 @@ EXPORT_SYMBOL_GPL(pwm_lpss_byt_info); const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = { .clk_rate = 19200000, .npwm = 1, + .base_unit_bits = 16, }; EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info); @@ -57,6 +58,7 @@ EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info); const struct pwm_lpss_boardinfo pwm_lpss_bxt_info = { .clk_rate = 19200000, .npwm = 4, + .base_unit_bits = 22, }; EXPORT_SYMBOL_GPL(pwm_lpss_bxt_info); @@ -79,28 +81,37 @@ static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value) writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM); } +static void pwm_lpss_update(struct pwm_device *pwm) +{ + pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE); + /* Give it some time to propagate */ + usleep_range(10, 50); +} + static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) { struct pwm_lpss_chip *lpwm = to_lpwm(chip); u8 on_time_div; - unsigned long c; - unsigned long long base_unit, freq = NSECS_PER_SEC; + unsigned long c, base_unit_range; + unsigned long long base_unit, freq = NSEC_PER_SEC; u32 ctrl; do_div(freq, period_ns); - /* The equation is: base_unit = ((freq / c) * 65536) + correction */ - base_unit = freq * 65536; + /* + * The equation is: + * base_unit = ((freq / c) * base_unit_range) + correction + */ + base_unit_range = BIT(lpwm->info->base_unit_bits); + base_unit = freq * base_unit_range; - c = lpwm->clk_rate; + c = lpwm->info->clk_rate; if (!c) return -EINVAL; do_div(base_unit, c); base_unit += PWM_DIVISION_CORRECTION; - if (base_unit > PWM_LIMIT) - return -EINVAL; if (duty_ns <= 0) duty_ns = 1; @@ -109,13 +120,20 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm, pm_runtime_get_sync(chip->dev); ctrl = pwm_lpss_read(pwm); - ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK); - ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT; + ctrl &= ~PWM_ON_TIME_DIV_MASK; + ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT); + base_unit &= (base_unit_range - 1); + ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT; ctrl |= on_time_div; - /* request PWM to update on next cycle */ - ctrl |= PWM_SW_UPDATE; pwm_lpss_write(pwm, ctrl); + /* + * If the PWM is already enabled we need to notify the hardware + * about the change by setting PWM_SW_UPDATE. + */ + if (pwm_is_enabled(pwm)) + pwm_lpss_update(pwm); + pm_runtime_put(chip->dev); return 0; @@ -124,6 +142,12 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm, static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm) { pm_runtime_get_sync(chip->dev); + + /* + * Hardware must first see PWM_SW_UPDATE before the PWM can be + * enabled. + */ + pwm_lpss_update(pwm); pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE); return 0; } @@ -135,7 +159,6 @@ static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm) } static const struct pwm_ops pwm_lpss_ops = { - .free = pwm_lpss_disable, .config = pwm_lpss_config, .enable = pwm_lpss_enable, .disable = pwm_lpss_disable, @@ -156,7 +179,7 @@ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r, if (IS_ERR(lpwm->regs)) return ERR_CAST(lpwm->regs); - lpwm->clk_rate = info->clk_rate; + lpwm->info = info; lpwm->chip.dev = dev; lpwm->chip.ops = &pwm_lpss_ops; lpwm->chip.base = -1; |