mediatek: pwm: add pwm driver for MediaTek SoCs

This driver support the standard PWM API for
MediaTek MT7623, MT7622 and MT7629 SoCs

Signed-off-by: Sam Shih <sam.shih@mediatek.com>

drivers/pwm/Kconfig

@@ -23,6 +23,13 @@ config PWM_IMX
 	help
 	  This PWM is found i.MX27 and later i.MX SoCs.
 
+config PWM_MTK
+	bool "Enable support for MediaTek PWM"
+	depends on DM_PWM
+	help
+	  This PWM is found on MT7622, MT7623, and MT7629. It supports a
+	  programmable period and duty cycle.
+
 config PWM_ROCKCHIP
 	bool "Enable support for the Rockchip PWM"
 	depends on DM_PWM

drivers/pwm/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_DM_PWM)		+= pwm-uclass.o
 
 obj-$(CONFIG_PWM_EXYNOS)	+= exynos_pwm.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o pwm-imx-util.o
+obj-$(CONFIG_PWM_MTK)		+= pwm-mtk.o
 obj-$(CONFIG_PWM_ROCKCHIP)	+= rk_pwm.o
 obj-$(CONFIG_PWM_SANDBOX)	+= sandbox_pwm.o
 obj-$(CONFIG_PWM_TEGRA)		+= tegra_pwm.o

drivers/pwm/pwm-mtk.c

@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 MediaTek Inc. All Rights Reserved.
+ *
+ * Author: Sam Shih <sam.shih@mediatek.com>
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <pwm.h>
+#include <div64.h>
+#include <linux/bitops.h>
+#include <linux/io.h>
+
+/* PWM registers and bits definitions */
+#define PWMCON			0x00
+#define PWMHDUR			0x04
+#define PWMLDUR			0x08
+#define PWMGDUR			0x0c
+#define PWMWAVENUM		0x28
+#define PWMDWIDTH		0x2c
+#define PWM45DWIDTH_FIXUP	0x30
+#define PWMTHRES		0x30
+#define PWM45THRES_FIXUP	0x34
+
+#define PWM_CLK_DIV_MAX		7
+#define MAX_PWM_NUM		8
+
+#define NSEC_PER_SEC 1000000000L
+
+static const unsigned int mtk_pwm_reg_offset[] = {
+	0x0010, 0x0050, 0x0090, 0x00d0, 0x0110, 0x0150, 0x0190, 0x0220
+};
+
+struct mtk_pwm_soc {
+	unsigned int num_pwms;
+	bool pwm45_fixup;
+};
+
+struct mtk_pwm_priv {
+	void __iomem *base;
+	struct clk top_clk;
+	struct clk main_clk;
+	struct clk pwm_clks[MAX_PWM_NUM];
+	const struct mtk_pwm_soc *soc;
+};
+
+static void mtk_pwm_w32(struct udevice *dev, uint channel, uint reg, uint val)
+{
+	struct mtk_pwm_priv *priv = dev_get_priv(dev);
+	u32 offset = mtk_pwm_reg_offset[channel];
+
+	writel(val, priv->base + offset + reg);
+}
+
+static int mtk_pwm_set_config(struct udevice *dev, uint channel,
+			      uint period_ns, uint duty_ns)
+{
+	struct mtk_pwm_priv *priv = dev_get_priv(dev);
+	u32 clkdiv = 0, clksel = 0, cnt_period, cnt_duty,
+	    reg_width = PWMDWIDTH, reg_thres = PWMTHRES;
+	u64 resolution;
+	int ret = 0;
+
+	clk_enable(&priv->top_clk);
+	clk_enable(&priv->main_clk);
+	/* Using resolution in picosecond gets accuracy higher */
+	resolution = (u64)NSEC_PER_SEC * 1000;
+	do_div(resolution, clk_get_rate(&priv->pwm_clks[channel]));
+	cnt_period = DIV_ROUND_CLOSEST_ULL((u64)period_ns * 1000, resolution);
+	while (cnt_period > 8191) {
+		resolution *= 2;
+		clkdiv++;
+		cnt_period = DIV_ROUND_CLOSEST_ULL((u64)period_ns * 1000,
+						   resolution);
+		if (clkdiv > PWM_CLK_DIV_MAX && clksel == 0) {
+			clksel = 1;
+			clkdiv = 0;
+			resolution = (u64)NSEC_PER_SEC * 1000 * 1625;
+			do_div(resolution,
+			       clk_get_rate(&priv->pwm_clks[channel]));
+			cnt_period = DIV_ROUND_CLOSEST_ULL(
+					(u64)period_ns * 1000, resolution);
+			clk_enable(&priv->pwm_clks[channel]);
+		}
+	}
+	if (clkdiv > PWM_CLK_DIV_MAX && clksel == 1) {
+		printf("pwm period %u not supported\n", period_ns);
+		return -EINVAL;
+	}
+	if (priv->soc->pwm45_fixup && channel > 2) {
+		/*
+		 * PWM[4,5] has distinct offset for PWMDWIDTH and PWMTHRES
+		 * from the other PWMs on MT7623.
+		 */
+		reg_width = PWM45DWIDTH_FIXUP;
+		reg_thres = PWM45THRES_FIXUP;
+	}
+	cnt_duty = DIV_ROUND_CLOSEST_ULL((u64)duty_ns * 1000, resolution);
+	if (clksel == 1)
+		mtk_pwm_w32(dev, channel, PWMCON, BIT(15) | BIT(3) | clkdiv);
+	else
+		mtk_pwm_w32(dev, channel, PWMCON, BIT(15) | clkdiv);
+	mtk_pwm_w32(dev, channel, reg_width, cnt_period);
+	mtk_pwm_w32(dev, channel, reg_thres, cnt_duty);
+
+	return ret;
+};
+
+static int mtk_pwm_set_enable(struct udevice *dev, uint channel, bool enable)
+{
+	struct mtk_pwm_priv *priv = dev_get_priv(dev);
+	u32 val = 0;
+
+	val = readl(priv->base);
+	if (enable)
+		val |= BIT(channel);
+	else
+		val &= ~BIT(channel);
+	writel(val, priv->base);
+
+	return 0;
+};
+
+static int mtk_pwm_probe(struct udevice *dev)
+{
+	struct mtk_pwm_priv *priv = dev_get_priv(dev);
+	int ret = 0;
+	int i;
+
+	priv->soc = (struct mtk_pwm_soc *)dev_get_driver_data(dev);
+	priv->base = (void __iomem *)devfdt_get_addr(dev);
+	if (!priv->base)
+		return -EINVAL;
+	ret = clk_get_by_name(dev, "top", &priv->top_clk);
+	if (ret < 0)
+		return ret;
+	ret = clk_get_by_name(dev, "main", &priv->main_clk);
+	if (ret < 0)
+		return ret;
+	for (i = 0; i < priv->soc->num_pwms; i++) {
+		char name[8];
+
+		snprintf(name, sizeof(name), "pwm%d", i + 1);
+		ret = clk_get_by_name(dev, name, &priv->pwm_clks[i]);
+		if (ret < 0)
+			return ret;
+	}
+
+	return ret;
+}
+
+static const struct pwm_ops mtk_pwm_ops = {
+	.set_config	= mtk_pwm_set_config,
+	.set_enable	= mtk_pwm_set_enable,
+};
+
+static const struct mtk_pwm_soc mt7622_data = {
+	.num_pwms = 6,
+	.pwm45_fixup = false,
+};
+
+static const struct mtk_pwm_soc mt7623_data = {
+	.num_pwms = 5,
+	.pwm45_fixup = true,
+};
+
+static const struct mtk_pwm_soc mt7629_data = {
+	.num_pwms = 1,
+	.pwm45_fixup = false,
+};
+
+static const struct udevice_id mtk_pwm_ids[] = {
+	{ .compatible = "mediatek,mt7622-pwm", .data = (ulong)&mt7622_data },
+	{ .compatible = "mediatek,mt7623-pwm", .data = (ulong)&mt7623_data },
+	{ .compatible = "mediatek,mt7629-pwm", .data = (ulong)&mt7629_data },
+	{ }
+};
+
+U_BOOT_DRIVER(mtk_pwm) = {
+	.name = "mtk_pwm",
+	.id = UCLASS_PWM,
+	.of_match = mtk_pwm_ids,
+	.ops = &mtk_pwm_ops,
+	.probe = mtk_pwm_probe,
+	.priv_auto_alloc_size = sizeof(struct mtk_pwm_priv),
+};