[U-Boot] [PATCH v2 12/25] exynos: pwm: Add a driver for the exynos5 PWM

Simon Glass
2016-02-22T04:08:49Z

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>
---

Changes in v2: None

arch/arm/cpu/armv7/s5p-common/timer.c | 3 +
drivers/pwm/Kconfig | 9 +++
drivers/pwm/Makefile | 1 +
drivers/pwm/exynos_pwm.c | 120 ++++++++++++++++++++++++++++++++++
4 files changed, 133 insertions(+)
create mode 100644 drivers/pwm/exynos_pwm.c

diff --git a/arch/arm/cpu/armv7/s5p-common/timer.c b/arch/arm/cpu/armv7/s5p-common/timer.c
index 949abb1..b63036c 100644
--- a/arch/arm/cpu/armv7/s5p-common/timer.c
+++ b/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;
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 6f0d61e..37ea2b8 100644
--- a/drivers/pwm/Kconfig
+++ b/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
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index fd414b1..af39347 100644
--- a/drivers/pwm/Makefile
+++ b/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
diff --git a/drivers/pwm/exynos_pwm.c b/drivers/pwm/exynos_pwm.c
new file mode 100644
index 0000000..a0edafc
--- /dev/null
+++ b/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),
+};
--
2.7.0.rc3.207.g0ac5344