exynos: pwm: Add a driver for the exynos5 PWM

This driver supports the standard PWM API. There are 5 PWMs. Four are used
normally and the last is normally used as a timer.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

arch/arm/cpu/armv7/s5p-common/timer.c

@@ -12,6 +12,9 @@
 #include <asm/io.h>
 #include <asm/arch/pwm.h>
 #include <asm/arch/clk.h>
+
+/* Use the old PWM interface for now */
+#undef CONFIG_DM_PWM
 #include <pwm.h>
 
 DECLARE_GLOBAL_DATA_PTR;

drivers/pwm/Kconfig

@@ -9,6 +9,15 @@ config DM_PWM
 	  frequency/period can be controlled along with the proportion of that
 	  time that the signal is high.
 
+config PWM_EXYNOS
+	bool "Enable support for the Exynos PWM"
+	depends on DM_PWM
+	help
+	  This PWM is found on Samsung Exynos 5250 and other Samsung SoCs. It
+	  supports a programmable period and duty cycle. A 32-bit counter is
+	  used. It provides 5 channels which can be independently
+	  programmed. Channel 4 (the last) is normally used as a timer.
+
 config PWM_ROCKCHIP
 	bool "Enable support for the Rockchip PWM"
 	depends on DM_PWM

drivers/pwm/Makefile

@@ -15,4 +15,5 @@ obj-$(CONFIG_PWM_ROCKCHIP) += rk_pwm.o
 obj-$(CONFIG_PWM_IMX) += pwm-imx.o pwm-imx-util.o
 ifdef CONFIG_DM_PWM
 obj-$(CONFIG_PWM_TEGRA) += tegra_pwm.o
+obj-$(CONFIG_PWM_EXYNOS) += exynos_pwm.o
 endif

drivers/pwm/exynos_pwm.c

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <pwm.h>
+#include <asm/io.h>
+#include <asm/arch/clk.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/pwm.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct exynos_pwm_priv {
+	struct s5p_timer *regs;
+};
+
+static int exynos_pwm_set_config(struct udevice *dev, uint channel,
+				uint period_ns, uint duty_ns)
+{
+	struct exynos_pwm_priv *priv = dev_get_priv(dev);
+	struct s5p_timer *regs = priv->regs;
+	unsigned int offset, prescaler;
+	uint div = 4, rate, rate_ns;
+	u32 val;
+	u32 tcnt, tcmp, tcon;
+
+	if (channel >= 5)
+		return -EINVAL;
+	debug("%s: Configure '%s' channel %u, period_ns %u, duty_ns %u\n",
+	      __func__, dev->name, channel, period_ns, duty_ns);
+
+	val = readl(&regs->tcfg0);
+	prescaler = (channel < 2 ? val : (val >> 8)) & 0xff;
+	div = (readl(&regs->tcfg1) >> MUX_DIV_SHIFT(channel)) & 0xf;
+
+	rate = get_pwm_clk() / ((prescaler + 1) * (1 << div));
+	debug("%s: pwm_clk %lu, rate %u\n", __func__, get_pwm_clk(), rate);
+
+	if (channel < 4) {
+		rate_ns = 1000000000 / rate;
+		tcnt = period_ns / rate_ns;
+		tcmp = duty_ns / rate_ns;
+		debug("%s: tcnt %u, tcmp %u\n", __func__, tcnt, tcmp);
+		offset = channel * 3;
+		writel(tcnt, &regs->tcntb0 + offset);
+		writel(tcmp, &regs->tcmpb0 + offset);
+	}
+
+	tcon = readl(&regs->tcon);
+	tcon |= TCON_UPDATE(channel);
+	if (channel < 4)
+		tcon |= TCON_AUTO_RELOAD(channel);
+	else
+		tcon |= TCON4_AUTO_RELOAD;
+	writel(tcon, &regs->tcon);
+
+	tcon &= ~TCON_UPDATE(channel);
+	writel(tcon, &regs->tcon);
+
+	return 0;
+}
+
+static int exynos_pwm_set_enable(struct udevice *dev, uint channel,
+				 bool enable)
+{
+	struct exynos_pwm_priv *priv = dev_get_priv(dev);
+	struct s5p_timer *regs = priv->regs;
+	u32 mask;
+
+	if (channel >= 4)
+		return -EINVAL;
+	debug("%s: Enable '%s' channel %u\n", __func__, dev->name, channel);
+	mask = TCON_START(channel);
+	clrsetbits_le32(&regs->tcon, mask, enable ? mask : 0);
+
+	return 0;
+}
+
+static int exynos_pwm_probe(struct udevice *dev)
+{
+	struct exynos_pwm_priv *priv = dev_get_priv(dev);
+	struct s5p_timer *regs = priv->regs;
+
+	writel(PRESCALER_0 | PRESCALER_1 << 8, &regs->tcfg0);
+
+	return 0;
+}
+
+static int exynos_pwm_ofdata_to_platdata(struct udevice *dev)
+{
+	struct exynos_pwm_priv *priv = dev_get_priv(dev);
+
+	priv->regs = (struct s5p_timer *)dev_get_addr(dev);
+
+	return 0;
+}
+
+static const struct pwm_ops exynos_pwm_ops = {
+	.set_config	= exynos_pwm_set_config,
+	.set_enable	= exynos_pwm_set_enable,
+};
+
+static const struct udevice_id exynos_channels[] = {
+	{ .compatible = "samsung,exynos4210-pwm" },
+	{ }
+};
+
+U_BOOT_DRIVER(exynos_pwm) = {
+	.name	= "exynos_pwm",
+	.id	= UCLASS_PWM,
+	.of_match = exynos_channels,
+	.ops	= &exynos_pwm_ops,
+	.probe	= exynos_pwm_probe,
+	.ofdata_to_platdata	= exynos_pwm_ofdata_to_platdata,
+	.priv_auto_alloc_size	= sizeof(struct exynos_pwm_priv),
+};