pwm: imx: Provide atomic PWM support for i.MX PWMv2

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>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 67 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index d557279446ed..34f3031d5c40 100644
--- a/drivers/pwm/pwm-imx.c
+++ b/drivers/pwm/pwm-imx.c
@@ -248,6 +248,72 @@ 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;
+
+                /*
+                 * 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 {
+                        ret = clk_prepare_enable(imx->clk_per);
+                        if (ret)
+                                return ret;
+
+                        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 if (cstate.enabled) {
+                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);
@@ -279,6 +345,7 @@ static const struct pwm_ops imx_pwm_ops_v1 = {
 };
 
 static const struct pwm_ops imx_pwm_ops_v2 = {
+        .apply = imx_pwm_apply_v2,
         .enable = imx_pwm_enable,
         .disable = imx_pwm_disable,
         .config = imx_pwm_config,