linux-kernel - [PATCH 6/8] pwm: dwc: add timer clock

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Message-Id: <20220805165033.140958-7-ben.dooks@sifive.com>
Date:   Fri,  5 Aug 2022 17:50:31 +0100
From:   Ben Dooks <ben.dooks@...ive.com>
To:     linux-pwm@...r.kernel.org
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lee Jones <lee.jones@...aro.org>,
        u.kleine-koenig@...gutronix.de,
        Thierry Reding <thierry.reding@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Greentime Hu <greentime.hu@...ive.com>,
        jarkko.nikula@...ux.intel.com,
        William Salmon <william.salmon@...ive.com>,
        Jude Onyenegecha --subject-prefix=PATCH v3 
        <jude.onyenegecha@...ive.com>, Ben Dooks <ben.dooks@...ive.com>
Subject: [PATCH 6/8] pwm: dwc: add timer clock

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@...ive.com>
---
v2:
  - removed the ifdef and merged the other clock patch in here
---
 drivers/pwm/pwm-dwc.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/pwm/pwm-dwc.c b/drivers/pwm/pwm-dwc.c
index d5f2df6fee62..5c319d0e3d52 100644
--- a/drivers/pwm/pwm-dwc.c
+++ b/drivers/pwm/pwm-dwc.c
@@ -18,6 +18,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/clk.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/pwm.h>
@@ -35,7 +36,6 @@
 #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)
@@ -54,6 +54,8 @@ struct dwc_pwm_ctx {
 struct dwc_pwm {
 	struct pwm_chip chip;
 	void __iomem *base;
+	struct clk *clk;
+	unsigned int clk_ns;
 	struct dwc_pwm_ctx ctx[DWC_TIMERS_TOTAL];
 };
 #define to_dwc_pwm(p)	(container_of((p), struct dwc_pwm, chip))
@@ -96,13 +98,13 @@ 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;
@@ -177,12 +179,12 @@ static void 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;
 
@@ -205,6 +207,7 @@ static 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;
@@ -336,6 +339,14 @@ static int dwc_pwm_plat_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, PTR_ERR(dwc->base),
 				     "failed to map IO\n");
 
+	dwc->clk = devm_clk_get(dev, "timer");
+	if (IS_ERR(dwc->clk))
+		return dev_err_probe(dev, PTR_ERR(dwc->clk),
+				     "failed to get timer clock\n");
+
+	clk_prepare_enable(dwc->clk);
+	dwc->clk_ns = 1000000000 / clk_get_rate(dwc->clk);
+
 	ret = pwmchip_add(&dwc->chip);
 	if (ret)
 		return ret;
@@ -347,6 +358,7 @@ static int dwc_pwm_plat_remove(struct platform_device *pdev)
 {
 	struct dwc_pwm *dwc = platform_get_drvdata(pdev);
 
+	clk_disable_unprepare(dwc->clk);
 	pwmchip_remove(&dwc->chip);
 	return 0;
 }
-- 
2.35.1