On Wed, Nov 7, 2012 at 4:44 PM, Peter Ujfalusi <peter.ujfalusi@xxxxxx> wrote:
> The driver supports the following PWM outputs:
> TWL4030 PWM0 and PWM1
> TWL6030 PWM1 and PWM2
>
> On TWL4030 the PWM signals are muxed. Upon requesting the PWM the driver
> will select the correct mux so the PWM can be used. When the PWM has been
> freed the original configuration going to be restored.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
> ---
> drivers/pwm/Kconfig | 10 ++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-twl.c | 304 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 315 insertions(+)
> create mode 100644 drivers/pwm/pwm-twl.c
>
<snip>
> --- /dev/null
> +++ b/drivers/pwm/pwm-twl.c
<snip>
> +
> +static int twl4030_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + int ret;
> + u8 val;
> +
> + ret = twl_i2c_read_u8(TWL4030_MODULE_INTBR, &val, TWL4030_GPBR1_REG);
> + if (ret < 0) {
> + dev_err(chip->dev, "%s: Failed to read GPBR1\n", pwm->label);
> + return ret;
> + }
> +
> + val |= TWL4030_PWM_TOGGLE(pwm->hwpwm, TWL4030_PWMX_BITS);
In my experience doing it like this doesn't work reliably, i.e.
sometimes it just won't enable. I had to first set CLK_ENABLE bit, and
then ENABLE bit with separate i2c write. Perhaps it needs a cycle or
two of 32k clock or something (that doesn't seem to be documented
though).
> +
> + ret = twl_i2c_write_u8(TWL4030_MODULE_INTBR, val, TWL4030_GPBR1_REG);
> + if (ret < 0)
> + dev_err(chip->dev, "%s: Failed to enable PWM\n", pwm->label);
> +
> + return ret;
> +}
> +
> +static void twl4030_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + int ret;
> + u8 val;
> +
> + ret = twl_i2c_read_u8(TWL4030_MODULE_INTBR, &val, TWL4030_GPBR1_REG);
> + if (ret < 0) {
> + dev_err(chip->dev, "%s: Failed to read GPBR1\n", pwm->label);
> + return;
> + }
> +
> + val &= ~TWL4030_PWM_TOGGLE(pwm->hwpwm, TWL4030_PWMX_BITS);
Same problem here, I would sometimes get LED stuck at full brightness
after this, first clearing ENABLE and then CLK_ENABLE fixed it (we
have charger LED connected to PWM1 on pandora).
> +
> + ret = twl_i2c_write_u8(TWL4030_MODULE_INTBR, val, TWL4030_GPBR1_REG);
> + if (ret < 0)
> + dev_err(chip->dev, "%s: Failed to disable PWM\n", pwm->label);
> +}
> +
> +static int twl4030_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct twl_pwm_chip *twl = container_of(chip, struct twl_pwm_chip,
> + chip);
> + int ret;
> + u8 val, mask, bits;
> +
> + ret = twl_i2c_read_u8(TWL4030_MODULE_INTBR, &val, TWL4030_PMBR1_REG);
> + if (ret < 0) {
> + dev_err(chip->dev, "%s: Failed to read PMBR1\n", pwm->label);
> + return ret;
> + }
> +
> + if (pwm->hwpwm) {
> + /* PWM 1 */
> + mask = TWL4030_GPIO7_VIBRASYNC_PWM1_MASK;
> + bits = TWL4030_GPIO7_VIBRASYNC_PWM1_PWM1;
> + } else {
> + /* PWM 0 */
> + mask = TWL4030_GPIO6_PWM0_MUTE_MASK;
> + bits = TWL4030_GPIO6_PWM0_MUTE_PWM0;
> + }
> +
> + /* Save the current MUX configuration for the PWM */
> + twl->twl4030_pwm_mux &= ~mask;
> + twl->twl4030_pwm_mux |= (val & mask);
Do we really need this mask clearing here? After probe twl4030_pwm_mux
should be zero, and if twl4030_pwm_request is called twice you don't
clear the important bits before |=, I think 'twl4030_pwm_mux = val &
mask' would be better here.
--
Gražvydas
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