pwm: dwc: make timer clock configurable

Add a configurable clock base rate for the pwm as when being built
for non-PCI the block may be sourced from an internal clock.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230907161242.67190-3-ben.dooks@codethink.co.uk
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

Author: bjdooks-ct

drivers/pwm/pwm-dwc-core.c

@@ -49,13 +49,13 @@ static int __dwc_pwm_configure_timer(struct dwc_pwm *dwc,
 	 * periods and check are the result within HW limits between 1 and
 	 * 2^32 periods.
 	 */
-	tmp = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, DWC_CLK_PERIOD_NS);
+	tmp = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, dwc->clk_ns);
 	if (tmp < 1 || tmp > (1ULL << 32))
 		return -ERANGE;
 	low = tmp - 1;
 
 	tmp = DIV_ROUND_CLOSEST_ULL(state->period - state->duty_cycle,
-				    DWC_CLK_PERIOD_NS);
+				    dwc->clk_ns);
 	if (tmp < 1 || tmp > (1ULL << 32))
 		return -ERANGE;
 	high = tmp - 1;
@@ -130,12 +130,12 @@ static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	duty = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(pwm->hwpwm));
 	duty += 1;
-	duty *= DWC_CLK_PERIOD_NS;
+	duty *= dwc->clk_ns;
 	state->duty_cycle = duty;
 
 	period = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(pwm->hwpwm));
 	period += 1;
-	period *= DWC_CLK_PERIOD_NS;
+	period *= dwc->clk_ns;
 	period += duty;
 	state->period = period;
 
@@ -159,6 +159,7 @@ struct dwc_pwm *dwc_pwm_alloc(struct device *dev)
 	if (!dwc)
 		return NULL;
 
+	dwc->clk_ns = 10;
 	dwc->chip.dev = dev;
 	dwc->chip.ops = &dwc_pwm_ops;
 	dwc->chip.npwm = DWC_TIMERS_TOTAL;

drivers/pwm/pwm-dwc.h

@@ -24,7 +24,6 @@ MODULE_IMPORT_NS(dwc_pwm);
 #define DWC_TIMERS_COMP_VERSION	0xac
 
 #define DWC_TIMERS_TOTAL	8
-#define DWC_CLK_PERIOD_NS	10
 
 /* Timer Control Register */
 #define DWC_TIM_CTRL_EN		BIT(0)
@@ -43,6 +42,7 @@ struct dwc_pwm_ctx {
 struct dwc_pwm {
 	struct pwm_chip chip;
 	void __iomem *base;
+	unsigned int clk_ns;
 	struct dwc_pwm_ctx ctx[DWC_TIMERS_TOTAL];
 };
 #define to_dwc_pwm(p)	(container_of((p), struct dwc_pwm, chip))