pwm: sophgo: add driver for Sophgo SG2042 PWM

Add a PWM driver for PWM controller in Sophgo SG2042 SoC.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
Link: https://lore.kernel.org/r/ae8ea1bf0bb0a09336cd8b7f627a994630524bba.1738737617.git.unicorn_wang@outlook.com
[ukleinek: Drop unneeded reset_control_assert() from error path]
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

drivers/pwm/Kconfig

@@ -584,6 +584,16 @@ config PWM_SL28CPLD
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-sl28cpld.
 
+config PWM_SOPHGO_SG2042
+	tristate "Sophgo SG2042 PWM support"
+	depends on ARCH_SOPHGO || COMPILE_TEST
+	help
+	  PWM driver for the PWM controller on Sophgo SG2042 SoC. The PWM
+	  controller supports outputing 4 channels of PWM waveforms.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm_sophgo_sg2042.
+
 config PWM_SPEAR
 	tristate "STMicroelectronics SPEAr PWM support"
 	depends on PLAT_SPEAR || COMPILE_TEST

drivers/pwm/Makefile

@@ -53,6 +53,7 @@ obj-$(CONFIG_PWM_RZ_MTU3)	+= pwm-rz-mtu3.o
 obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_SIFIVE)	+= pwm-sifive.o
 obj-$(CONFIG_PWM_SL28CPLD)	+= pwm-sl28cpld.o
+obj-$(CONFIG_PWM_SOPHGO_SG2042)	+= pwm-sophgo-sg2042.o
 obj-$(CONFIG_PWM_SPEAR)		+= pwm-spear.o
 obj-$(CONFIG_PWM_SPRD)		+= pwm-sprd.o
 obj-$(CONFIG_PWM_STI)		+= pwm-sti.o

drivers/pwm/pwm-sophgo-sg2042.c

@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sophgo SG2042 PWM Controller Driver
+ *
+ * Copyright (C) 2024 Sophgo Technology Inc.
+ * Copyright (C) 2024 Chen Wang <unicorn_wang@outlook.com>
+ *
+ * Limitations:
+ * - After reset, the output of the PWM channel is always high.
+ *   The value of HLPERIOD/PERIOD is 0.
+ * - When HLPERIOD or PERIOD is reconfigured, PWM will start to
+ *   output waveforms with the new configuration after completing
+ *   the running period.
+ * - When PERIOD and HLPERIOD is set to 0, the PWM wave output will
+ *   be stopped and the output is pulled to high.
+ * See the datasheet [1] for more details.
+ * [1]:https://github.com/sophgo/sophgo-doc/tree/main/SG2042/TRM
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/reset.h>
+
+/*
+ * Offset RegisterName
+ * 0x0000 HLPERIOD0
+ * 0x0004 PERIOD0
+ * 0x0008 HLPERIOD1
+ * 0x000C PERIOD1
+ * 0x0010 HLPERIOD2
+ * 0x0014 PERIOD2
+ * 0x0018 HLPERIOD3
+ * 0x001C PERIOD3
+ * Four groups and every group is composed of HLPERIOD & PERIOD
+ */
+#define SG2042_PWM_HLPERIOD(chan) ((chan) * 8 + 0)
+#define SG2042_PWM_PERIOD(chan) ((chan) * 8 + 4)
+
+#define SG2042_PWM_CHANNELNUM	4
+
+/**
+ * struct sg2042_pwm_ddata - private driver data
+ * @base:		base address of mapped PWM registers
+ * @clk_rate_hz:	rate of base clock in HZ
+ */
+struct sg2042_pwm_ddata {
+	void __iomem *base;
+	unsigned long clk_rate_hz;
+};
+
+/*
+ * period_ticks: PERIOD
+ * hlperiod_ticks: HLPERIOD
+ */
+static void pwm_sg2042_config(struct sg2042_pwm_ddata *ddata, unsigned int chan,
+			      u32 period_ticks, u32 hlperiod_ticks)
+{
+	void __iomem *base = ddata->base;
+
+	writel(period_ticks, base + SG2042_PWM_PERIOD(chan));
+	writel(hlperiod_ticks, base + SG2042_PWM_HLPERIOD(chan));
+}
+
+static int pwm_sg2042_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			    const struct pwm_state *state)
+{
+	struct sg2042_pwm_ddata *ddata = pwmchip_get_drvdata(chip);
+	u32 hlperiod_ticks;
+	u32 period_ticks;
+
+	if (state->polarity == PWM_POLARITY_INVERSED)
+		return -EINVAL;
+
+	if (!state->enabled) {
+		pwm_sg2042_config(ddata, pwm->hwpwm, 0, 0);
+		return 0;
+	}
+
+	/*
+	 * Duration of High level (duty_cycle) = HLPERIOD x Period_of_input_clk
+	 * Duration of One Cycle (period) = PERIOD x Period_of_input_clk
+	 */
+	period_ticks = min(mul_u64_u64_div_u64(ddata->clk_rate_hz, state->period, NSEC_PER_SEC), U32_MAX);
+	hlperiod_ticks = min(mul_u64_u64_div_u64(ddata->clk_rate_hz, state->duty_cycle, NSEC_PER_SEC), U32_MAX);
+
+	dev_dbg(pwmchip_parent(chip), "chan[%u]: PERIOD=%u, HLPERIOD=%u\n",
+		pwm->hwpwm, period_ticks, hlperiod_ticks);
+
+	pwm_sg2042_config(ddata, pwm->hwpwm, period_ticks, hlperiod_ticks);
+
+	return 0;
+}
+
+static int pwm_sg2042_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				struct pwm_state *state)
+{
+	struct sg2042_pwm_ddata *ddata = pwmchip_get_drvdata(chip);
+	unsigned int chan = pwm->hwpwm;
+	u32 hlperiod_ticks;
+	u32 period_ticks;
+
+	period_ticks = readl(ddata->base + SG2042_PWM_PERIOD(chan));
+	hlperiod_ticks = readl(ddata->base + SG2042_PWM_HLPERIOD(chan));
+
+	if (!period_ticks) {
+		state->enabled = false;
+		return 0;
+	}
+
+	if (hlperiod_ticks > period_ticks)
+		hlperiod_ticks = period_ticks;
+
+	state->enabled = true;
+	state->period = DIV_ROUND_UP_ULL((u64)period_ticks * NSEC_PER_SEC, ddata->clk_rate_hz);
+	state->duty_cycle = DIV_ROUND_UP_ULL((u64)hlperiod_ticks * NSEC_PER_SEC, ddata->clk_rate_hz);
+	state->polarity = PWM_POLARITY_NORMAL;
+
+	return 0;
+}
+
+static const struct pwm_ops pwm_sg2042_ops = {
+	.apply = pwm_sg2042_apply,
+	.get_state = pwm_sg2042_get_state,
+};
+
+static const struct of_device_id sg2042_pwm_ids[] = {
+	{ .compatible = "sophgo,sg2042-pwm" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sg2042_pwm_ids);
+
+static int pwm_sg2042_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct sg2042_pwm_ddata *ddata;
+	struct reset_control *rst;
+	struct pwm_chip *chip;
+	struct clk *clk;
+	int ret;
+
+	chip = devm_pwmchip_alloc(dev, SG2042_PWM_CHANNELNUM, sizeof(*ddata));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	ddata = pwmchip_get_drvdata(chip);
+
+	ddata->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ddata->base))
+		return PTR_ERR(ddata->base);
+
+	clk = devm_clk_get_enabled(dev, "apb");
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk), "Failed to get base clk\n");
+
+	ret = devm_clk_rate_exclusive_get(dev, clk);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get exclusive rate\n");
+
+	ddata->clk_rate_hz = clk_get_rate(clk);
+	/* period = PERIOD * NSEC_PER_SEC / clk_rate_hz */
+	if (!ddata->clk_rate_hz || ddata->clk_rate_hz > NSEC_PER_SEC)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid clock rate: %lu\n", ddata->clk_rate_hz);
+
+	rst = devm_reset_control_get_optional_shared_deasserted(dev, NULL);
+	if (IS_ERR(rst))
+		return dev_err_probe(dev, PTR_ERR(rst), "Failed to get reset\n");
+
+	chip->ops = &pwm_sg2042_ops;
+	chip->atomic = true;
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to register PWM chip\n");
+
+	return 0;
+}
+
+static struct platform_driver pwm_sg2042_driver = {
+	.driver	= {
+		.name = "sg2042-pwm",
+		.of_match_table = sg2042_pwm_ids,
+	},
+	.probe = pwm_sg2042_probe,
+};
+module_platform_driver(pwm_sg2042_driver);
+
+MODULE_AUTHOR("Chen Wang");
+MODULE_DESCRIPTION("Sophgo SG2042 PWM driver");
+MODULE_LICENSE("GPL");