[RFC 6/7] pwm: Add Tegra2 SoC support
Thierry Reding
thierry.reding at avionic-design.de
Tue Dec 20 21:32:17 EST 2011
Signed-off-by: Thierry Reding <thierry.reding at avionic-design.de>
---
arch/arm/boot/dts/tegra20.dtsi | 6 +
arch/arm/mach-tegra/board-dt.c | 1 +
arch/arm/mach-tegra/devices.c | 15 +++
arch/arm/mach-tegra/devices.h | 1 +
drivers/pwm/Kconfig | 5 +
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-tegra.c | 274 ++++++++++++++++++++++++++++++++++++++++
7 files changed, 303 insertions(+), 0 deletions(-)
create mode 100644 drivers/pwm/pwm-tegra.c
diff --git a/arch/arm/boot/dts/tegra20.dtsi b/arch/arm/boot/dts/tegra20.dtsi
index 168545e..1c58dce 100644
--- a/arch/arm/boot/dts/tegra20.dtsi
+++ b/arch/arm/boot/dts/tegra20.dtsi
@@ -122,6 +122,12 @@
interrupts = < 0 91 0x04 >;
};
+ pwm: pwm at 7000a000 {
+ compatible = "nvidia,tegra20-pwm";
+ reg = <0x7000a000 0x100>;
+ #pwm-cells = <2>;
+ };
+
sdhci at c8000000 {
compatible = "nvidia,tegra20-sdhci";
reg = <0xc8000000 0x200>;
diff --git a/arch/arm/mach-tegra/board-dt.c b/arch/arm/mach-tegra/board-dt.c
index 2fa599d..387146c 100644
--- a/arch/arm/mach-tegra/board-dt.c
+++ b/arch/arm/mach-tegra/board-dt.c
@@ -81,6 +81,7 @@ struct of_dev_auxdata tegra20_auxdata_lookup[] __initdata = {
&tegra_ehci2_device.dev.platform_data),
OF_DEV_AUXDATA("nvidia,tegra20-ehci", TEGRA_USB3_BASE, "tegra-ehci.2",
&tegra_ehci3_device.dev.platform_data),
+ OF_DEV_AUXDATA("nvidia,tegra20-pwm", TEGRA_PWFM_BASE, "tegra-pwm", NULL),
{}
};
diff --git a/arch/arm/mach-tegra/devices.c b/arch/arm/mach-tegra/devices.c
index 7a2a02d..c67d85d 100644
--- a/arch/arm/mach-tegra/devices.c
+++ b/arch/arm/mach-tegra/devices.c
@@ -704,3 +704,18 @@ struct platform_device tegra_pcm_device = {
.name = "tegra-pcm-audio",
.id = -1,
};
+
+static struct resource tegra_pwm_resources[] = {
+ [0] = {
+ .start = TEGRA_PWFM_BASE,
+ .end = TEGRA_PWFM_BASE + TEGRA_PWFM_SIZE - 1,
+ .flags = IORESOURCE_MEM,
+ },
+};
+
+struct platform_device tegra_pwm_device = {
+ .name = "tegra-pwm",
+ .id = -1,
+ .num_resources = ARRAY_SIZE(tegra_pwm_resources),
+ .resource = tegra_pwm_resources,
+};
diff --git a/arch/arm/mach-tegra/devices.h b/arch/arm/mach-tegra/devices.h
index 873ecb2..a8a5e25 100644
--- a/arch/arm/mach-tegra/devices.h
+++ b/arch/arm/mach-tegra/devices.h
@@ -48,5 +48,6 @@ extern struct platform_device tegra_i2s_device1;
extern struct platform_device tegra_i2s_device2;
extern struct platform_device tegra_das_device;
extern struct platform_device tegra_pcm_device;
+extern struct platform_device tegra_pwm_device;
#endif
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 93c1052..7c6a137 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -9,4 +9,9 @@ menuconfig PWM
if PWM
+config PWM_TEGRA
+ tristate "NVIDIA Tegra PWM support"
+ depends on ARCH_TEGRA
+ default n
+
endif
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 3469c3d..12300f5 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -1 +1,2 @@
obj-$(CONFIG_PWM) += core.o
+obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o
diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
new file mode 100644
index 0000000..fd2f075
--- /dev/null
+++ b/drivers/pwm/pwm-tegra.c
@@ -0,0 +1,274 @@
+/*
+ * drivers/pwm/pwm-tegra.c
+ *
+ * Tegra pulse-width-modulation controller driver
+ *
+ * Copyright (c) 2010, NVIDIA Corporation.
+ * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer at pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define PWM_ENABLE (1 << 31)
+#define PWM_DUTY_WIDTH 8
+#define PWM_DUTY_SHIFT 16
+#define PWM_SCALE_WIDTH 13
+#define PWM_SCALE_SHIFT 0
+
+struct tegra_pwm_chip {
+ struct pwm_chip chip;
+ struct device *dev;
+
+ struct clk *clk;
+
+ int clk_enb[4];
+ void __iomem *mmio_base;
+};
+
+static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
+{
+ return container_of(chip, struct tegra_pwm_chip, chip);
+}
+
+static inline int pwm_writel(struct tegra_pwm_chip *chip, unsigned int pwm,
+ unsigned long val)
+{
+ unsigned long offset = pwm << 4;
+ int rc;
+
+ rc = clk_enable(chip->clk);
+ if (WARN_ON(rc))
+ return rc;
+
+ writel(val, chip->mmio_base + offset);
+ clk_disable(chip->clk);
+
+ return 0;
+}
+
+static int tegra_pwm_config(struct pwm_chip *chip, unsigned int pwm,
+ int duty_ns, int period_ns)
+{
+ struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
+ unsigned int num = pwm - chip->base;
+ unsigned long long c;
+ unsigned long rate, hz;
+ u32 val = 0;
+
+ /* convert from duty_ns / period_ns to a fixed number of duty
+ * ticks per (1 << PWM_DUTY_WIDTH) cycles.
+ */
+ c = duty_ns * ((1 << PWM_DUTY_WIDTH) - 1);
+ do_div(c, period_ns);
+
+ val = (u32)c << PWM_DUTY_SHIFT;
+
+ /* compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
+ * cycles at the PWM clock rate will take period_ns nanoseconds.
+ */
+ rate = clk_get_rate(pc->clk) >> PWM_DUTY_WIDTH;
+ hz = 1000000000ul / period_ns;
+
+ rate = (rate + (hz / 2)) / hz;
+
+ /* Since the actual PWM divider is the register's frequency divider
+ * field minus 1, we need to decrement to get the correct value to write
+ * to the register.
+ */
+ if (rate > 0)
+ rate--;
+
+ /* Make sure that the rate will fit in the register's frequency divider
+ * field.
+ */
+ if (rate >> PWM_SCALE_WIDTH)
+ return -EINVAL;
+
+ val |= (rate << PWM_SCALE_SHIFT);
+
+ /* the struct clk may be shared across multiple PWM devices, so
+ * only enable the PWM if this device has been enabled
+ */
+ if (pc->clk_enb[num])
+ val |= PWM_ENABLE;
+
+ return pwm_writel(pc, num, val);
+}
+
+static int tegra_pwm_enable(struct pwm_chip *chip, unsigned int pwm)
+{
+ struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
+ unsigned int num = pwm - chip->base;
+ int rc = 0;
+
+ if (!pc->clk_enb[num]) {
+ rc = clk_enable(pc->clk);
+ if (!rc) {
+ unsigned long offset = num << 4;
+ u32 val;
+
+ val = readl(pc->mmio_base + offset);
+ val |= PWM_ENABLE;
+ writel(val, pc->mmio_base + offset);
+
+ pc->clk_enb[num] = 1;
+ }
+ }
+
+ return 0;
+}
+
+static void tegra_pwm_disable(struct pwm_chip *chip, unsigned int pwm)
+{
+ struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
+ unsigned int num = pwm - chip->base;
+
+ if (pc->clk_enb[num]) {
+ unsigned long offset = num << 4;
+ u32 val;
+
+ val = readl(pc->mmio_base + offset);
+ val &= ~PWM_ENABLE;
+ writel(val, pc->mmio_base + offset);
+
+ clk_disable(pc->clk);
+ pc->clk_enb[num] = 0;
+ }
+}
+
+static struct pwm_ops tegra_pwm_ops = {
+ .config = tegra_pwm_config,
+ .enable = tegra_pwm_enable,
+ .disable = tegra_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static int tegra_pwm_probe(struct platform_device *pdev)
+{
+ struct tegra_pwm_chip *pwm;
+ struct resource *r;
+ int ret;
+
+ pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+ if (!pwm) {
+ dev_err(&pdev->dev, "failed to allocate memory\n");
+ return -ENOMEM;
+ }
+
+ pwm->dev = &pdev->dev;
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!r) {
+ dev_err(&pdev->dev, "no memory resources defined\n");
+ return -ENODEV;
+ }
+
+ r = devm_request_mem_region(&pdev->dev, r->start, resource_size(r),
+ pdev->name);
+ if (!r) {
+ dev_err(&pdev->dev, "failed to request memory\n");
+ return -EBUSY;
+ }
+
+ pwm->mmio_base = devm_ioremap(&pdev->dev, r->start, resource_size(r));
+ if (!pwm->mmio_base) {
+ dev_err(&pdev->dev, "failed to ioremap() region\n");
+ return -ENODEV;
+ }
+
+ platform_set_drvdata(pdev, pwm);
+
+ pwm->clk = clk_get(&pdev->dev, NULL);
+ if (IS_ERR(pwm->clk))
+ return PTR_ERR(pwm->clk);
+
+ pwm->chip.label = "tegra-pwm";
+ pwm->chip.ops = &tegra_pwm_ops;
+ pwm->chip.base = -1;
+ pwm->chip.npwm = 4;
+
+#ifdef CONFIG_OF_PWM
+ pwm->chip.of_node = pdev->dev.of_node;
+#endif
+
+ ret = pwmchip_add(&pwm->chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
+ clk_put(pwm->clk);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int __devexit tegra_pwm_remove(struct platform_device *pdev)
+{
+ struct tegra_pwm_chip *pwm = platform_get_drvdata(pdev);
+ int i;
+
+ if (WARN_ON(!pwm))
+ return -ENODEV;
+
+ for (i = 0; i < 4; i++) {
+ pwm_writel(pwm, i, 0);
+
+ if (pwm->clk_enb[i])
+ clk_disable(pwm->clk);
+ }
+
+ clk_put(pwm->clk);
+
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static struct of_device_id tegra_pwm_of_match[] = {
+ { .compatible = "nvidia,tegra20-pwm" },
+ { }
+};
+#endif
+
+static struct platform_driver tegra_pwm_driver = {
+ .driver = {
+ .name = "tegra-pwm",
+ .of_match_table = of_match_ptr(tegra_pwm_of_match),
+ },
+ .probe = tegra_pwm_probe,
+ .remove = __devexit_p(tegra_pwm_remove),
+};
+
+static int __init tegra_pwm_init(void)
+{
+ return platform_driver_register(&tegra_pwm_driver);
+}
+subsys_initcall(tegra_pwm_init);
+
+static void __exit tegra_pwm_exit(void)
+{
+ platform_driver_unregister(&tegra_pwm_driver);
+}
+module_exit(tegra_pwm_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("NVIDIA Corporation");
--
1.7.8
More information about the devicetree-discuss
mailing list