[PATCH 2/2] pwm: Add Nuvoton PWM controller support

[Chi-Wen Weng <cwweng.linux@gmail.com>]

This commit adds a generic PWM framework driver for Nuvoton MA35D1
PWM controller.

Signed-off-by: Chi-Wen Weng <cwweng.linux@gmail.com>
---
 drivers/pwm/Kconfig      |   9 +++
 drivers/pwm/Makefile     |   1 +
 drivers/pwm/pwm-ma35d1.c | 169 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 179 insertions(+)
 create mode 100644 drivers/pwm/pwm-ma35d1.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 0915c1e7df16..97b9e83af020 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -411,6 +411,15 @@ config PWM_LPSS_PLATFORM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-lpss-platform.
 
+config PWM_MA35D1
+	tristate "Nuvoton MA35D1 PWM support"
+	depends on ARCH_MA35 || COMPILE_TEST
+	help
+	  Generic PWM framework driver for Nuvoton MA35D1.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-ma35d1.
+
 config PWM_MESON
 	tristate "Amlogic Meson PWM driver"
 	depends on ARCH_MESON || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 9081e0c0e9e0..c1d3a1d8add0 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
 obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
 obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o
 obj-$(CONFIG_PWM_LPSS_PLATFORM)	+= pwm-lpss-platform.o
+obj-$(CONFIG_PWM_MA35D1)	+= pwm-ma35d1.o
 obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o
 obj-$(CONFIG_PWM_MEDIATEK)	+= pwm-mediatek.o
 obj-$(CONFIG_PWM_MICROCHIP_CORE)	+= pwm-microchip-core.o
diff --git a/drivers/pwm/pwm-ma35d1.c b/drivers/pwm/pwm-ma35d1.c
new file mode 100644
index 000000000000..dc2f1f494a91
--- /dev/null
+++ b/drivers/pwm/pwm-ma35d1.c
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the Nuvoton MA35D1 PWM controller
+ *
+ * Copyright (C) 2024 Nuvoton Corporation
+ *               Chi-Wen Weng <cwweng@nuvoton.com>
+ */
+
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/math64.h>
+
+/* The following are registers for PWM controller */
+#define REG_PWM_CTL0            (0x00)
+#define REG_PWM_CNTEN           (0x20)
+#define REG_PWM_PERIOD0         (0x30)
+#define REG_PWM_CMPDAT0         (0x50)
+#define REG_PWM_WGCTL0          (0xB0)
+#define REG_PWM_POLCTL          (0xD4)
+#define REG_PWM_POEN            (0xD8)
+
+#define PWM_TOTAL_CHANNELS      6
+#define PWM_CH_REG_SIZE         4
+
+struct nuvoton_pwm {
+	void __iomem *base;
+	u64 clkrate;
+};
+
+static inline struct nuvoton_pwm *to_nuvoton_pwm(struct pwm_chip *chip)
+{
+	return pwmchip_get_drvdata(chip);
+}
+
+static int nuvoton_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			     const struct pwm_state *state)
+{
+	struct nuvoton_pwm *nvtpwm;
+	unsigned int ch = pwm->hwpwm;
+
+	nvtpwm = to_nuvoton_pwm(chip);
+	if (state->enabled) {
+		u64 duty_cycles, period_cycles;
+
+		/* Calculate the duty and period cycles */
+		duty_cycles = mul_u64_u64_div_u64(nvtpwm->clkrate,
+						  state->duty_cycle, NSEC_PER_SEC);
+		if (duty_cycles > 0xFFFF)
+			duty_cycles = 0xFFFF;
+
+		period_cycles = mul_u64_u64_div_u64(nvtpwm->clkrate,
+						    state->period, NSEC_PER_SEC);
+		if (period_cycles > 0xFFFF)
+			period_cycles = 0xFFFF;
+
+		/* Write the duty and period cycles to registers */
+		writel(duty_cycles, nvtpwm->base + REG_PWM_CMPDAT0 + (ch * PWM_CH_REG_SIZE));
+		writel(period_cycles, nvtpwm->base + REG_PWM_PERIOD0 + (ch * PWM_CH_REG_SIZE));
+		/* Enable counter */
+		writel(readl(nvtpwm->base + REG_PWM_CNTEN) | BIT(ch),
+		       nvtpwm->base + REG_PWM_CNTEN);
+		/* Enable output */
+		writel(readl(nvtpwm->base + REG_PWM_POEN) | BIT(ch),
+		       nvtpwm->base + REG_PWM_POEN);
+	} else {
+		/* Disable counter */
+		writel(readl(nvtpwm->base + REG_PWM_CNTEN) & ~BIT(ch),
+		       nvtpwm->base + REG_PWM_CNTEN);
+		/* Disable output */
+		writel(readl(nvtpwm->base + REG_PWM_POEN) & ~BIT(ch),
+		       nvtpwm->base + REG_PWM_POEN);
+	}
+
+	/* Set polarity state to register */
+	if (state->polarity == PWM_POLARITY_NORMAL)
+		writel(readl(nvtpwm->base + REG_PWM_POLCTL) & ~BIT(ch),
+		       nvtpwm->base + REG_PWM_POLCTL);
+	else
+		writel(readl(nvtpwm->base + REG_PWM_POLCTL) | BIT(ch),
+		       nvtpwm->base + REG_PWM_POLCTL);
+
+	return 0;
+}
+
+static int nuvoton_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				 struct pwm_state *state)
+{
+	struct nuvoton_pwm *nvtpwm;
+	unsigned int duty_cycles, period_cycles, cnten, outen, polarity;
+	unsigned int ch = pwm->hwpwm;
+
+	nvtpwm = to_nuvoton_pwm(chip);
+
+	cnten = readl(nvtpwm->base + REG_PWM_CNTEN);
+	outen = readl(nvtpwm->base + REG_PWM_POEN);
+	duty_cycles = readl(nvtpwm->base + REG_PWM_CMPDAT0 + (ch * PWM_CH_REG_SIZE));
+	period_cycles = readl(nvtpwm->base + REG_PWM_PERIOD0 + (ch * PWM_CH_REG_SIZE));
+	polarity = readl(nvtpwm->base + REG_PWM_POLCTL) & BIT(ch);
+
+	state->enabled = (cnten & BIT(ch)) && (outen & BIT(ch));
+	state->polarity = polarity ? PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
+	state->duty_cycle = DIV64_U64_ROUND_UP((u64)duty_cycles * NSEC_PER_SEC, nvtpwm->clkrate);
+	state->period = DIV64_U64_ROUND_UP((u64)period_cycles * NSEC_PER_SEC, nvtpwm->clkrate);
+
+	return 0;
+}
+
+static const struct pwm_ops nuvoton_pwm_ops = {
+	.apply = nuvoton_pwm_apply,
+	.get_state = nuvoton_pwm_get_state,
+};
+
+static int nuvoton_pwm_probe(struct platform_device *pdev)
+{
+	struct pwm_chip *chip;
+	struct nuvoton_pwm *nvtpwm;
+	struct clk *clk;
+	int ret;
+
+	chip = devm_pwmchip_alloc(&pdev->dev, PWM_TOTAL_CHANNELS, sizeof(*nvtpwm));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+
+	nvtpwm = to_nuvoton_pwm(chip);
+
+	nvtpwm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(nvtpwm->base))
+		return PTR_ERR(nvtpwm->base);
+
+	clk = devm_clk_get_enabled(&pdev->dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(clk), "unable to get the clock");
+
+	nvtpwm->clkrate = clk_get_rate(clk);
+	if (nvtpwm->clkrate > NSEC_PER_SEC)
+		return dev_err_probe(&pdev->dev, -EINVAL, "pwm clock out of range");
+
+	chip->ops = &nuvoton_pwm_ops;
+
+	ret = devm_pwmchip_add(&pdev->dev, chip);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "unable to add pwm chip");
+
+	return 0;
+}
+
+static const struct of_device_id nuvoton_pwm_of_match[] = {
+	{ .compatible = "nuvoton,ma35d1-pwm" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, nuvoton_pwm_of_match);
+
+static struct platform_driver nuvoton_pwm_driver = {
+	.probe = nuvoton_pwm_probe,
+	.driver = {
+		.name = "nuvoton-pwm",
+		.of_match_table = nuvoton_pwm_of_match,
+	},
+};
+module_platform_driver(nuvoton_pwm_driver);
+
+MODULE_ALIAS("platform:nuvoton-pwm");
+MODULE_AUTHOR("Chi-Wen Weng <cwweng@nuvoton.com>");
+MODULE_DESCRIPTION("Nuvoton MA35D1 PWM driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1