[U-Boot] [PATCH v2 07/23] tegra: pwm: Add a driver for the tegra PWM

[Simon Glass]

This PWM supports four channels. The driver always uses the 32KHz clock,
and adjusts the duty cycle accordingly.

Signed-off-by: Simon Glass <s...@chromium.org>
---

Changes in v2: None

 arch/arm/include/asm/arch-tegra/pwm.h |  2 +
 drivers/pwm/Makefile                  |  3 ++
 drivers/pwm/tegra_pwm.c               | 85 +++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+)
 create mode 100644 drivers/pwm/tegra_pwm.c

diff --git a/arch/arm/include/asm/arch-tegra/pwm.h 
b/arch/arm/include/asm/arch-tegra/pwm.h
index 92dced4..eb2e465 100644
--- a/arch/arm/include/asm/arch-tegra/pwm.h
+++ b/arch/arm/include/asm/arch-tegra/pwm.h
@@ -27,6 +27,7 @@ struct pwm_ctlr {
 #define PWM_DIVIDER_SHIFT      0
 #define PWM_DIVIDER_MASK       (0x1FFF << PWM_DIVIDER_SHIFT)
 
+#ifndef CONFIG_PWM
 /**
  * Program the PWM with the given parameters.
  *
@@ -56,5 +57,6 @@ int pwm_request(const void *blob, int node, const char 
*prop_name);
  * @return 0 if ok, -1 if the device tree node was not found or invalid.
  */
 int pwm_init(const void *blob);
+#endif
 
 #endif /* __ASM_ARCH_TEGRA_PWM_H */
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index b6d8c16..fd414b1 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -13,3 +13,6 @@
 obj-$(CONFIG_DM_PWM) += pwm-uclass.o
 obj-$(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
+endif
diff --git a/drivers/pwm/tegra_pwm.c b/drivers/pwm/tegra_pwm.c
new file mode 100644
index 0000000..10e1fdc
--- /dev/null
+++ b/drivers/pwm/tegra_pwm.c
@@ -0,0 +1,85 @@
+/*
+ * 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/clock.h>
+#include <asm/arch/pwm.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct tegra_pwm_priv {
+       struct pwm_ctlr *regs;
+};
+
+static int tegra_pwm_set_config(struct udevice *dev, uint channel,
+                               uint period_ns, uint duty_ns)
+{
+       struct tegra_pwm_priv *priv = dev_get_priv(dev);
+       struct pwm_ctlr *regs = priv->regs;
+       uint pulse_width;
+       u32 reg;
+
+       if (channel >= 4)
+               return -EINVAL;
+       debug("%s: Configure '%s' channel %u\n", __func__, dev->name, channel);
+       /* We ignore the period here and just use 32KHz */
+       clock_start_periph_pll(PERIPH_ID_PWM, CLOCK_ID_SFROM32KHZ, 32768);
+
+       pulse_width = duty_ns * 255 / period_ns;
+
+       reg = pulse_width << PWM_WIDTH_SHIFT;
+       reg |= 1 << PWM_DIVIDER_SHIFT;
+       writel(reg, &regs[channel].control);
+       debug("%s: pulse_width=%u\n", __func__, pulse_width);
+
+       return 0;
+}
+
+static int tegra_pwm_set_enable(struct udevice *dev, uint channel, bool enable)
+{
+       struct tegra_pwm_priv *priv = dev_get_priv(dev);
+       struct pwm_ctlr *regs = priv->regs;
+
+       if (channel >= 4)
+               return -EINVAL;
+       debug("%s: Enable '%s' channel %u\n", __func__, dev->name, channel);
+       clrsetbits_le32(&regs[channel].control, PWM_ENABLE_MASK,
+                       enable ? PWM_ENABLE_MASK : 0);
+
+       return 0;
+}
+
+static int tegra_pwm_ofdata_to_platdata(struct udevice *dev)
+{
+       struct tegra_pwm_priv *priv = dev_get_priv(dev);
+
+       priv->regs = (struct pwm_ctlr *)dev_get_addr(dev);
+
+       return 0;
+}
+
+static const struct pwm_ops tegra_pwm_ops = {
+       .set_config     = tegra_pwm_set_config,
+       .set_enable     = tegra_pwm_set_enable,
+};
+
+static const struct udevice_id tegra_pwm_ids[] = {
+       { .compatible = "nvidia,tegra124-pwm" },
+       { .compatible = "nvidia,tegra20-pwm" },
+       { }
+};
+
+U_BOOT_DRIVER(tegra_pwm) = {
+       .name   = "tegra_pwm",
+       .id     = UCLASS_PWM,
+       .of_match = tegra_pwm_ids,
+       .ops    = &tegra_pwm_ops,
+       .ofdata_to_platdata     = tegra_pwm_ofdata_to_platdata,
+       .priv_auto_alloc_size   = sizeof(struct tegra_pwm_priv),
+};
-- 
2.7.0.rc3.207.g0ac5344

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