[PATCH v2] pwm: add CSR SiRFSoC PWM driver

Barry Song 21cnbao at gmail.com
Thu Jan 30 00:52:25 EST 2014


From: Rongjun Ying <Rongjun.ying at csr.com>

PWM controller of CSR SiRFSoC can generate 7 independent outputs. Each output
duty cycle can be adjusted by setting the corresponding wait & hold registers.

Supports 7 independent channel output: 6 for external(channel0-5) and 1 for
internal(channel6).

Supports wide frequency range: divide by 2 to 65536*2 of source clock.

Signed-off-by: Rongjun Ying <Rongjun.ying at csr.com>
Signed-off-by: Huayi Li <Huayi.Li at csr.com>
Signed-off-by: Barry Song <Baohua.Song at csr.com>
---
 -v2: clean the source clock of PWM wave, use OSC(26MHz)

 drivers/pwm/Kconfig    |    9 ++
 drivers/pwm/Makefile   |    1 +
 drivers/pwm/pwm-sirf.c |  294 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 304 insertions(+), 0 deletions(-)
 create mode 100644 drivers/pwm/pwm-sirf.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 7acab93..0a252f8 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -166,6 +166,15 @@ config PWM_SAMSUNG
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-samsung.
 
+config PWM_SIRF
+	tristate "SiRF PWM support"
+	depends on ARCH_SIRF
+	help
+	  Generic PWM framework driver for SiRF SoC.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-sirf.
+
 config PWM_SPEAR
 	tristate "STMicroelectronics SPEAr PWM support"
 	depends on PLAT_SPEAR
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 4abf337..49ab0d7 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_PWM_PUV3)		+= pwm-puv3.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
 obj-$(CONFIG_PWM_RENESAS_TPU)	+= pwm-renesas-tpu.o
 obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
+obj-$(CONFIG_PWM_SIRF)		+= pwm-sirf.o
 obj-$(CONFIG_PWM_SPEAR)		+= pwm-spear.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o
 obj-$(CONFIG_PWM_TIECAP)	+= pwm-tiecap.o
diff --git a/drivers/pwm/pwm-sirf.c b/drivers/pwm/pwm-sirf.c
new file mode 100644
index 0000000..1a5c5b7
--- /dev/null
+++ b/drivers/pwm/pwm-sirf.c
@@ -0,0 +1,294 @@
+/*
+ * SIRF serial SoC PWM device core driver
+ *
+ * Copyright (c) 2014 Cambridge Silicon Radio Limited, a CSR plc group company.
+ *
+ * Licensed under GPLv2 or later.
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/pwm.h>
+#include <linux/of.h>
+#include <linux/io.h>
+
+#define SIRF_PWM_SELECT_PRECLK			0x0
+#define SIRF_PWM_OE				0x4
+#define SIRF_PWM_ENABLE_PRECLOCK		0x8
+#define SIRF_PWM_ENABLE_POSTCLOCK		0xC
+#define SIRF_PWM_GET_WAIT_OFFSET(n)		(0x10 + 0x8*n)
+#define SIRF_PWM_GET_HOLD_OFFSET(n)		(0x14 + 0x8*n)
+
+#define SIRF_PWM_TR_STEP(n)			(0x48 + 0x8*n)
+#define SIRF_PWM_STEP_HOLD(n)			(0x4c + 0x8*n)
+
+#define SRC_FIELD_SIZE				3
+#define BYPASS_MODE_BIT				21
+#define TRANS_MODE_SELECT_BIT			7
+
+#define SIRF_PWM_CHL_NUM			7
+#define SIRF_PWM_BLS_GRP_NUM			16
+
+struct sirf_pwm {
+	void __iomem		*base;
+	struct clk		*clk;
+	struct pwm_chip		chip;
+};
+
+#define to_sirf_chip(chip)	container_of(chip, struct sirf_pwm, chip)
+
+static unsigned int sirf_pwm_ns_to_cycles(struct pwm_chip *chip, unsigned int time_ns)
+{
+	u64 dividend;
+	unsigned int cycle;
+	/*
+	 * on SiRFSoC, OSC input is const, we use it as the source to generate
+	 * PWM wave
+	 */
+#define SRC_OSC_RATE 26000000ULL
+	dividend = SRC_OSC_RATE * time_ns + NSEC_PER_SEC / 2;
+	do_div(dividend, NSEC_PER_SEC);
+
+	cycle = dividend & 0xFFFFFFFFUL;
+
+	return cycle > 1 ? cycle : 1;
+}
+
+static int sirf_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+		int duty_ns, int period_ns)
+{
+	unsigned int period_cycles, high_cycles, low_cycles;
+	unsigned int val;
+	struct sirf_pwm *spwm = to_sirf_chip(chip);
+
+	period_cycles = sirf_pwm_ns_to_cycles(chip, period_ns);
+
+	high_cycles = sirf_pwm_ns_to_cycles(chip, duty_ns);
+	low_cycles = period_cycles - high_cycles;
+
+	if (period_cycles == 1) {
+		/* bypass mode */
+		val = readl(spwm->base + SIRF_PWM_SELECT_PRECLK);
+		val |= 0x1 << (BYPASS_MODE_BIT + pwm->hwpwm);
+		writel(val, spwm->base + SIRF_PWM_SELECT_PRECLK);
+		dev_warn(chip->dev, "period is too short!\n");
+	} else {
+		/* divider mode */
+		val = readl(spwm->base + SIRF_PWM_SELECT_PRECLK);
+		val &= ~(0x1 << (BYPASS_MODE_BIT + pwm->hwpwm));
+		writel(val, spwm->base + SIRF_PWM_SELECT_PRECLK);
+
+		if (high_cycles == period_cycles) {
+			high_cycles--;
+			low_cycles = 1;
+		}
+
+		writel(high_cycles, spwm->base + SIRF_PWM_GET_WAIT_OFFSET(pwm->hwpwm));
+		writel(low_cycles, spwm->base + SIRF_PWM_GET_HOLD_OFFSET(pwm->hwpwm));
+	}
+
+	return 0;
+}
+
+static int sirf_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct sirf_pwm *spwm = to_sirf_chip(chip);
+	unsigned int val;
+
+	/* disable preclock */
+	val = readl(spwm->base + SIRF_PWM_ENABLE_PRECLOCK);
+	val &= ~(1 << pwm->hwpwm);
+	writel(val, spwm->base + SIRF_PWM_ENABLE_PRECLOCK);
+
+	/* select preclock source must after disable preclk*/
+	val = readl(spwm->base + SIRF_PWM_SELECT_PRECLK);
+	val &= ~(0x7 << (SRC_FIELD_SIZE * pwm->hwpwm));
+	writel(val, spwm->base + SIRF_PWM_SELECT_PRECLK);
+	/* wait for some time */
+	udelay(100);
+
+	/* enable preclock */
+	val = readl(spwm->base + SIRF_PWM_ENABLE_PRECLOCK);
+	val |= (1 << pwm->hwpwm);
+	writel(val, spwm->base + SIRF_PWM_ENABLE_PRECLOCK);
+
+	/* enable post clock*/
+	val = readl(spwm->base + SIRF_PWM_ENABLE_POSTCLOCK);
+	val |= (1 << pwm->hwpwm);
+	writel(val, spwm->base + SIRF_PWM_ENABLE_POSTCLOCK);
+
+	/* enable output */
+	val = readl(spwm->base + SIRF_PWM_OE);
+	val |= 1 << pwm->hwpwm;
+	val &= ~(1 << (pwm->hwpwm + TRANS_MODE_SELECT_BIT));
+
+	writel(val, spwm->base + SIRF_PWM_OE);
+
+	return 0;
+}
+
+static void sirf_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	unsigned int val;
+	struct sirf_pwm *spwm = to_sirf_chip(chip);
+	/* disable output */
+	val = readl(spwm->base + SIRF_PWM_OE);
+	val &= ~(1 << pwm->hwpwm);
+	writel(val, spwm->base + SIRF_PWM_OE);
+
+	/* disable postclock */
+	val = readl(spwm->base + SIRF_PWM_ENABLE_POSTCLOCK);
+	val &= ~(1 << pwm->hwpwm);
+	writel(val, spwm->base + SIRF_PWM_ENABLE_POSTCLOCK);
+
+	/* disable preclock */
+	val = readl(spwm->base + SIRF_PWM_ENABLE_PRECLOCK);
+	val &= ~(1 << pwm->hwpwm);
+	writel(val, spwm->base + SIRF_PWM_ENABLE_PRECLOCK);
+}
+
+static struct pwm_ops sirf_pwm_ops = {
+	.enable = sirf_pwm_enable,
+	.disable = sirf_pwm_disable,
+	.config = sirf_pwm_config,
+	.owner = THIS_MODULE,
+};
+
+static int sirf_pwm_probe(struct platform_device *pdev)
+{
+	struct sirf_pwm *spwm;
+	struct resource *mem_res;
+	int ret;
+
+	spwm = devm_kzalloc(&pdev->dev, sizeof(struct sirf_pwm),
+			GFP_KERNEL);
+	if (!spwm)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, spwm);
+
+	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	spwm->base = devm_ioremap_resource(&pdev->dev, mem_res);
+	if (!spwm->base)
+		return -ENOMEM;
+
+	spwm->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(spwm->clk)) {
+		dev_err(&pdev->dev, "Get clock failed.\n");
+		return PTR_ERR(spwm->clk);
+	}
+
+	clk_prepare_enable(spwm->clk);
+
+	spwm->chip.dev = &pdev->dev;
+	spwm->chip.ops = &sirf_pwm_ops;
+	spwm->chip.base = 0;
+	spwm->chip.npwm = SIRF_PWM_CHL_NUM;
+
+	ret = pwmchip_add(&spwm->chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to register pwm\n");
+		clk_disable_unprepare(spwm->clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int sirf_pwm_remove(struct platform_device *pdev)
+{
+	struct sirf_pwm *spwm = platform_get_drvdata(pdev);
+	clk_disable_unprepare(spwm->clk);
+
+	pwmchip_remove(&spwm->chip);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int sirf_pwm_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct sirf_pwm *spwm = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(spwm->clk);
+
+	return 0;
+}
+
+static void sirf_pwm_config_restore(struct sirf_pwm *spwm)
+{
+	struct pwm_device *pwm;
+	int i;
+
+	for (i = 0; i < spwm->chip.npwm; i++) {
+		pwm = &spwm->chip.pwms[i];
+		/*
+		 * while restoring from hibernation, state of pwm is enabled,
+		 * but PWM hardware is not re-enabled
+		 */
+		if (test_bit(PWMF_REQUESTED, &pwm->flags) &&
+		     test_bit(PWMF_ENABLED, &pwm->flags))
+			sirf_pwm_enable(&spwm->chip, pwm);
+	}
+}
+
+static int sirf_pwm_resume(struct device *dev)
+{
+	struct sirf_pwm *spwm = dev_get_drvdata(dev);
+
+	clk_prepare_enable(spwm->clk);
+
+	sirf_pwm_config_restore(spwm);
+
+	return 0;
+}
+
+static int sirf_pwm_restore(struct device *dev)
+{
+	struct sirf_pwm *spwm = dev_get_drvdata(dev);
+
+	/* back from hibernation, clock is already enabled */
+	sirf_pwm_config_restore(spwm);
+
+	return 0;
+}
+
+#else
+#define sirf_pwm_resume NULL
+#define sirf_pwm_suspend NULL
+#define sirf_pwm_restore NULL
+#endif
+
+static const struct dev_pm_ops sirf_pwm_pm_ops = {
+	.suspend = sirf_pwm_suspend,
+	.resume = sirf_pwm_resume,
+	.restore = sirf_pwm_restore,
+};
+
+static const struct of_device_id sirf_pwm_of_match[] = {
+	{ .compatible = "sirf,prima2-pwm", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sirf_pwm_of_match);
+
+static struct platform_driver sirf_pwm_driver = {
+	.driver = {
+		.name = "prima2-pwm",
+		.owner = THIS_MODULE,
+		.pm = &sirf_pwm_pm_ops,
+		.of_match_table = sirf_pwm_of_match,
+	},
+	.probe = sirf_pwm_probe,
+	.remove = sirf_pwm_remove,
+};
+
+module_platform_driver(sirf_pwm_driver);
+
+MODULE_DESCRIPTION("SIRF serial SoC PWM device core driver");
+MODULE_AUTHOR("RongJun Ying <Rongjun.Ying at csr.com>, "
+	"Huayi Li <huayi.li at csr.com>");
+MODULE_LICENSE("GPL v2");
-- 
1.7.5.4




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