diff options
Diffstat (limited to 'drivers/pwm/pwm-sifive.c')
| -rw-r--r-- | drivers/pwm/pwm-sifive.c | 117 |
1 files changed, 65 insertions, 52 deletions
diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c index e6d05a329002..2d4fa5e5fdd4 100644 --- a/drivers/pwm/pwm-sifive.c +++ b/drivers/pwm/pwm-sifive.c @@ -23,7 +23,7 @@ #define PWM_SIFIVE_PWMCFG 0x0 #define PWM_SIFIVE_PWMCOUNT 0x8 #define PWM_SIFIVE_PWMS 0x10 -#define PWM_SIFIVE_PWMCMP0 0x20 +#define PWM_SIFIVE_PWMCMP(i) (0x20 + 4 * (i)) /* PWMCFG fields */ #define PWM_SIFIVE_PWMCFG_SCALE GENMASK(3, 0) @@ -36,14 +36,12 @@ #define PWM_SIFIVE_PWMCFG_GANG BIT(24) #define PWM_SIFIVE_PWMCFG_IP BIT(28) -/* PWM_SIFIVE_SIZE_PWMCMP is used to calculate offset for pwmcmpX registers */ -#define PWM_SIFIVE_SIZE_PWMCMP 4 #define PWM_SIFIVE_CMPWIDTH 16 #define PWM_SIFIVE_DEFAULT_PERIOD 10000000 struct pwm_sifive_ddata { struct pwm_chip chip; - struct mutex lock; /* lock to protect user_count */ + struct mutex lock; /* lock to protect user_count and approx_period */ struct notifier_block notifier; struct clk *clk; void __iomem *regs; @@ -78,6 +76,7 @@ static void pwm_sifive_free(struct pwm_chip *chip, struct pwm_device *pwm) mutex_unlock(&ddata->lock); } +/* Called holding ddata->lock */ static void pwm_sifive_update_clock(struct pwm_sifive_ddata *ddata, unsigned long rate) { @@ -112,8 +111,7 @@ static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip); u32 duty, val; - duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP0 + - pwm->hwpwm * PWM_SIFIVE_SIZE_PWMCMP); + duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm)); state->enabled = duty > 0; @@ -127,24 +125,6 @@ static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm, state->polarity = PWM_POLARITY_INVERSED; } -static int pwm_sifive_enable(struct pwm_chip *chip, bool enable) -{ - struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip); - int ret; - - if (enable) { - ret = clk_enable(ddata->clk); - if (ret) { - dev_err(ddata->chip.dev, "Enable clk failed\n"); - return ret; - } - } else { - clk_disable(ddata->clk); - } - - return 0; -} - static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { @@ -159,13 +139,6 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, if (state->polarity != PWM_POLARITY_INVERSED) return -EINVAL; - ret = clk_enable(ddata->clk); - if (ret) { - dev_err(ddata->chip.dev, "Enable clk failed\n"); - return ret; - } - - mutex_lock(&ddata->lock); cur_state = pwm->state; enabled = cur_state.enabled; @@ -184,25 +157,36 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm, /* The hardware cannot generate a 100% duty cycle */ frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1); + mutex_lock(&ddata->lock); if (state->period != ddata->approx_period) { if (ddata->user_count != 1) { - ret = -EBUSY; - goto exit; + mutex_unlock(&ddata->lock); + return -EBUSY; } ddata->approx_period = state->period; pwm_sifive_update_clock(ddata, clk_get_rate(ddata->clk)); } + mutex_unlock(&ddata->lock); - writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP0 + - pwm->hwpwm * PWM_SIFIVE_SIZE_PWMCMP); + /* + * If the PWM is enabled the clk is already on. So only enable it + * conditionally to have it on exactly once afterwards independent of + * the PWM state. + */ + if (!enabled) { + ret = clk_enable(ddata->clk); + if (ret) { + dev_err(ddata->chip.dev, "Enable clk failed\n"); + return ret; + } + } - if (state->enabled != enabled) - pwm_sifive_enable(chip, state->enabled); + writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm)); -exit: - clk_disable(ddata->clk); - mutex_unlock(&ddata->lock); - return ret; + if (!state->enabled) + clk_disable(ddata->clk); + + return 0; } static const struct pwm_ops pwm_sifive_ops = { @@ -232,6 +216,8 @@ static int pwm_sifive_probe(struct platform_device *pdev) struct pwm_sifive_ddata *ddata; struct pwm_chip *chip; int ret; + u32 val; + unsigned int enabled_pwms = 0, enabled_clks = 1; ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL); if (!ddata) @@ -258,6 +244,33 @@ static int pwm_sifive_probe(struct platform_device *pdev) return ret; } + val = readl(ddata->regs + PWM_SIFIVE_PWMCFG); + if (val & PWM_SIFIVE_PWMCFG_EN_ALWAYS) { + unsigned int i; + + for (i = 0; i < chip->npwm; ++i) { + val = readl(ddata->regs + PWM_SIFIVE_PWMCMP(i)); + if (val > 0) + ++enabled_pwms; + } + } + + /* The clk should be on once for each running PWM. */ + if (enabled_pwms) { + while (enabled_clks < enabled_pwms) { + /* This is not expected to fail as the clk is already on */ + ret = clk_enable(ddata->clk); + if (unlikely(ret)) { + dev_err_probe(dev, ret, "Failed to enable clk\n"); + goto disable_clk; + } + ++enabled_clks; + } + } else { + clk_disable(ddata->clk); + enabled_clks = 0; + } + /* Watch for changes to underlying clock frequency */ ddata->notifier.notifier_call = pwm_sifive_clock_notifier; ret = clk_notifier_register(ddata->clk, &ddata->notifier); @@ -280,7 +293,11 @@ static int pwm_sifive_probe(struct platform_device *pdev) unregister_clk: clk_notifier_unregister(ddata->clk, &ddata->notifier); disable_clk: - clk_disable_unprepare(ddata->clk); + while (enabled_clks) { + clk_disable(ddata->clk); + --enabled_clks; + } + clk_unprepare(ddata->clk); return ret; } @@ -288,23 +305,19 @@ disable_clk: static int pwm_sifive_remove(struct platform_device *dev) { struct pwm_sifive_ddata *ddata = platform_get_drvdata(dev); - bool is_enabled = false; struct pwm_device *pwm; int ch; + pwmchip_remove(&ddata->chip); + clk_notifier_unregister(ddata->clk, &ddata->notifier); + for (ch = 0; ch < ddata->chip.npwm; ch++) { pwm = &ddata->chip.pwms[ch]; - if (pwm->state.enabled) { - is_enabled = true; - break; - } + if (pwm->state.enabled) + clk_disable(ddata->clk); } - if (is_enabled) - clk_disable(ddata->clk); - clk_disable_unprepare(ddata->clk); - pwmchip_remove(&ddata->chip); - clk_notifier_unregister(ddata->clk, &ddata->notifier); + clk_unprepare(ddata->clk); return 0; } |