[PATCH v4 07/11] pwm: imx: Provide atomic PWM support for i.MX PWMv2

Lukasz Majewski
2017-01-04T23:39:17Z

This commit provides apply() callback implementation for i.MX's PWMv2.

Suggested-by: Stefan Agner <stefan@agner.ch>
Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
Changes for v4:
- Avoid recalculation of PWM parameters when disabling PWM signal
- Unconditionally call clk_prepare_enable(imx->clk_per) and
clk_disable_unprepare(imx->clk_per)

Changes for v3:
- Remove ipg clock enable/disable functions

Changes for v2:
- None
---
drivers/pwm/pwm-imx.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 67 insertions(+)

diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index 60cdc5c..134dd66 100644
--- a/drivers/pwm/pwm-imx.c
+++ b/drivers/pwm/pwm-imx.c
@@ -249,6 +249,72 @@ static int imx_pwm_config(struct pwm_chip *chip,
return ret;
}

+static int imx_pwm_apply_v2(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ unsigned long period_cycles, duty_cycles, prescale;
+ struct imx_chip *imx = to_imx_chip(chip);
+ struct pwm_state cstate;
+ unsigned long long c;
+ int ret;
+
+ pwm_get_state(pwm, &cstate);
+
+ if (state->enabled) {
+ c = clk_get_rate(imx->clk_per);
+ c *= state->period;
+
+ do_div(c, 1000000000);
+ period_cycles = c;
+
+ prescale = period_cycles / 0x10000 + 1;
+
+ period_cycles /= prescale;
+ c = (unsigned long long)period_cycles * state->duty_cycle;
+ do_div(c, state->period);
+ duty_cycles = c;
+
+ /*
+ * according to imx pwm RM, the real period value should be
+ * PERIOD value in PWMPR plus 2.
+ */
+ if (period_cycles > 2)
+ period_cycles -= 2;
+ else
+ period_cycles = 0;
+
+ ret = clk_prepare_enable(imx->clk_per);
+ if (ret)
+ return ret;
+
+ /*
+ * Wait for a free FIFO slot if the PWM is already enabled, and
+ * flush the FIFO if the PWM was disabled and is about to be
+ * enabled.
+ */
+ if (cstate.enabled)
+ imx_pwm_wait_fifo_slot(chip, pwm);
+ else if (state->enabled)
+ imx_pwm_sw_reset(chip);
+
+ writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
+ writel(period_cycles, imx->mmio_base + MX3_PWMPR);
+
+ writel(MX3_PWMCR_PRESCALER(prescale) |
+ MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
+ MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH |
+ MX3_PWMCR_EN,
+ imx->mmio_base + MX3_PWMCR);
+
+ } else {
+ writel(0, imx->mmio_base + MX3_PWMCR);
+
+ clk_disable_unprepare(imx->clk_per);
+ }
+
+ return 0;
+}
+
static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct imx_chip *imx = to_imx_chip(chip);
@@ -280,6 +346,7 @@ static struct pwm_ops imx_pwm_ops_v1 = {
};

static struct pwm_ops imx_pwm_ops_v2 = {
+ .apply = imx_pwm_apply_v2,
.enable = imx_pwm_enable,
.disable = imx_pwm_disable,
.config = imx_pwm_config,
--
2.1.4