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pwm: vt8500: Ensure PWM clock is enabled during pwm_config 

This patch corrects a bug reported by Peter Vasil.

When all PWMs are disabled, PWM module may be disabled during
calls to pwm_config. This patch enables/disables the clock in
pwm_config to ensure the module is active before register read/
writes.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Tested-by: Peter Vasil <petervasil@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
This commit is contained in:
Tony Prisk 2012-11-20 06:44:46 +13:00 committed by Thierry Reding
parent 2f9569f7ce
commit 422470a826
1 changed files with 12 additions and 2 deletions
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14
drivers/pwm/pwm-vt8500.c
View File

@ -62,6 +62,13 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
unsigned long long c;
unsigned long period_cycles, prescale, pv, dc;
int err;
err = clk_enable(vt8500->clk);
if (err < 0) {
dev_err(chip->dev, "failed to enable clock\n");
return err;
}
c = clk_get_rate(vt8500->clk);
c = c * period_ns;
@ -75,8 +82,10 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
if (pv > 4095)
pv = 4095;
if (prescale > 1023)
if (prescale > 1023) {
clk_disable(vt8500->clk);
return -EINVAL;
}
c = (unsigned long long)pv * duty_ns;
do_div(c, period_ns);
@ -91,6 +100,7 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 3));
writel(dc, vt8500->base + 0xc + (pwm->hwpwm << 4));
clk_disable(vt8500->clk);
return 0;
}
@ -103,7 +113,7 @@ static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
if (err < 0) {
dev_err(chip->dev, "failed to enable clock\n");
return err;
};
}
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
writel(5, vt8500->base + (pwm->hwpwm << 4));