Patchwork [V2,24/69] ST SPEAr: Adding support for ST's PWM IP

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Submitter Viresh KUMAR
Date Oct. 1, 2010, 11:55 a.m.
Message ID <1aff89823163d30cc109447d53935f2729158e59.1285933331.git.viresh.kumar@st.com>
Download mbox | patch
Permalink /patch/66343/
State New
Headers show

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Viresh KUMAR - Oct. 1, 2010, 11:55 a.m.
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
---
 arch/arm/mach-spear3xx/include/mach/generic.h |    1 +
 arch/arm/mach-spear3xx/spear320.c             |   17 +
 arch/arm/mach-spear3xx/spear320_evb.c         |    1 +
 arch/arm/plat-spear/Kconfig                   |    7 +
 arch/arm/plat-spear/Makefile                  |    1 +
 arch/arm/plat-spear/pwm.c                     |  484 +++++++++++++++++++++++++
 6 files changed, 511 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/plat-spear/pwm.c

Patch

diff --git a/arch/arm/mach-spear3xx/include/mach/generic.h b/arch/arm/mach-spear3xx/include/mach/generic.h
index 70f7ee2..447de7e 100644
--- a/arch/arm/mach-spear3xx/include/mach/generic.h
+++ b/arch/arm/mach-spear3xx/include/mach/generic.h
@@ -174,6 +174,7 @@  void __init spear310_init(void);
 extern struct amba_device clcd_device;
 extern struct platform_device i2c1_device;
 extern struct platform_device plgpio_device;
+extern struct platform_device pwm_device;
 
 /* pad mux modes */
 extern struct pmx_mode auto_net_smii_mode;
diff --git a/arch/arm/mach-spear3xx/spear320.c b/arch/arm/mach-spear3xx/spear320.c
index bfb21ae..75e7890 100644
--- a/arch/arm/mach-spear3xx/spear320.c
+++ b/arch/arm/mach-spear3xx/spear320.c
@@ -452,6 +452,23 @@  struct platform_device plgpio_device = {
 	.resource = plgpio_resources,
 };
 
+/* pwm device registeration */
+static struct resource pwm_resources[] = {
+	{
+		.start = SPEAR320_PWM_BASE,
+		.end = SPEAR320_PWM_BASE + SZ_4K - 1,
+		.flags = IORESOURCE_MEM,
+	},
+};
+
+struct platform_device pwm_device = {
+	.name = "pwm",
+	.id = -1,
+	.num_resources = ARRAY_SIZE(pwm_resources),
+	.resource = pwm_resources,
+};
+
+
 /* spear3xx shared irq */
 struct shirq_dev_config shirq_ras1_config[] = {
 	{
diff --git a/arch/arm/mach-spear3xx/spear320_evb.c b/arch/arm/mach-spear3xx/spear320_evb.c
index f90a9b8..943eddc 100644
--- a/arch/arm/mach-spear3xx/spear320_evb.c
+++ b/arch/arm/mach-spear3xx/spear320_evb.c
@@ -57,6 +57,7 @@  static struct platform_device *plat_devs[] __initdata = {
 	/* spear320 specific devices */
 	&i2c1_device,
 	&plgpio_device,
+	&pwm_device,
 };
 
 static void __init spear320_evb_init(void)
diff --git a/arch/arm/plat-spear/Kconfig b/arch/arm/plat-spear/Kconfig
index 29a25d2..80f402b 100644
--- a/arch/arm/plat-spear/Kconfig
+++ b/arch/arm/plat-spear/Kconfig
@@ -36,4 +36,11 @@  source "arch/arm/mach-spear13xx/Kconfig"
 source "arch/arm/mach-spear3xx/Kconfig"
 source "arch/arm/mach-spear6xx/Kconfig"
 
+config SPEAR_PWM
+	tristate "SPEAr Pulse Width Modulator"
+	depends on MACH_SPEAR320
+	default y
+	help
+	  Support for ST Microelectronics Pulse Width Modulator present on SPEAr Platform.
+
 endif
diff --git a/arch/arm/plat-spear/Makefile b/arch/arm/plat-spear/Makefile
index c31892a..0e29587 100644
--- a/arch/arm/plat-spear/Makefile
+++ b/arch/arm/plat-spear/Makefile
@@ -8,6 +8,7 @@  obj-y	:= clcd.o clock.o time.o
 obj-$(CONFIG_ARCH_SPEAR3XX)	+= shirq.o padmux.o
 obj-$(CONFIG_MACH_SPEAR310)	+= plgpio.o
 obj-$(CONFIG_MACH_SPEAR320)	+= plgpio.o
+obj-$(CONFIG_SPEAR_PWM)		+= pwm.o
 
 obj-$(CONFIG_BOARD_SPEAR1300_EVB)	+= i2c_eval_board.o
 obj-$(CONFIG_BOARD_SPEAR300_EVB)	+= i2c_eval_board.o
diff --git a/arch/arm/plat-spear/pwm.c b/arch/arm/plat-spear/pwm.c
new file mode 100644
index 0000000..307c725
--- /dev/null
+++ b/arch/arm/plat-spear/pwm.c
@@ -0,0 +1,484 @@ 
+/*
+ * arch/arm/plat-spear/pwm.c
+ *
+ * ST Microelectronics SPEAr Pulse Width Modulator driver
+ *
+ * Copyright (C) 2010 ST Microelectronics
+ * Viresh Kumar<viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+/* PWM registers and bits definitions */
+#define PWMCR			0x00
+#define PWMDCR			0x04
+#define PWMPCR			0x08
+
+#define PWM_EN_MASK		0x1
+#define MIN_PRESCALE		0x00
+#define MAX_PRESCALE		0x3FFF
+#define PRESCALE_SHIFT		2
+#define MIN_DUTY		0x0001
+#define MAX_DUTY		0xFFFF
+#define MAX_PERIOD		0xFFFF
+#define MIN_PERIOD		0x0001
+
+#define PWM_DEVICE_PER_IP	4
+#define PWM_DEVICE_OFFSET	0x10
+
+/* lock for pwm_list */
+static DEFINE_SPINLOCK(list_lock);
+/* list of all pwm ips available in system */
+static LIST_HEAD(pwm_list);
+
+/**
+ * struct pwm_device: struct representing pwm device/channel
+ *
+ * pwmd_id: id of pwm device
+ * pwm: pointer to parent pwm ip
+ * label: used for storing label passed in pwm_request
+ * offset: base address offset from parent pwm mmio_base
+ * busy: represents usage status of a pwm device
+ * lock: lock specific to a pwm device
+ * node: node for adding device to parent pwm's devices list
+ *
+ * Each pwm IP contains four independent pwm device/channels. Some or all of
+ * which may be present in our configuration.
+ */
+struct pwm_device {
+	unsigned pwmd_id;
+	struct pwm *pwm;
+	const char *label;
+	unsigned offset;
+	unsigned busy;
+	spinlock_t lock;
+	struct list_head node;
+};
+
+/**
+ * struct pwm: struct representing pwm ip
+ *
+ * id: id of pwm ip
+ * mmio_base: base address of pwm
+ * clk: pointer to clk structure of pwm ip
+ * clk_enabled: clock enable status
+ * pdev: pointer to pdev structure of pwm
+ * lock: lock specific to current pwm ip
+ * devices: list of devices/childrens of pwm ip
+ * node: node for adding pwm to global list of all pwm ips
+ */
+struct pwm {
+	unsigned id;
+	void __iomem *mmio_base;
+	struct clk *clk;
+	int clk_enabled;
+	struct platform_device *pdev;
+	spinlock_t lock;
+	struct list_head devices;
+	struct list_head node;
+};
+
+/*
+ * period_ns = 10^9 * (PRESCALE + 1) * PV / PWM_CLK_RATE
+ * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
+ *
+ * PV = (PWM_CLK_RATE * period_ns)/ (10^9 * (PRESCALE + 1))
+ * DC = (PWM_CLK_RATE * duty_ns)/ (10^9 * (PRESCALE + 1))
+ */
+int pwm_config(struct pwm_device *pwmd, int duty_ns, int period_ns)
+{
+	u64 val, div, clk_rate;
+	unsigned long prescale = MIN_PRESCALE, pv, dc;
+	int ret = 0;
+
+	if (!pwmd) {
+		pr_err("pwm: config - NULL pwm device pointer\n");
+		return -EFAULT;
+	}
+
+	if (period_ns == 0 || duty_ns > period_ns) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	/* TODO: Need to optimize this loop */
+	while (1) {
+		div = 1000000000;
+		div *= 1 + prescale;
+		clk_rate = clk_get_rate(pwmd->pwm->clk);
+		val = clk_rate * period_ns;
+		pv = div64_u64(val, div);
+		val = clk_rate * duty_ns;
+		dc = div64_u64(val, div);
+
+		if ((pv == 0) || (dc == 0)) {
+			ret = -EINVAL;
+			goto err;
+		}
+		if ((pv > MAX_PERIOD) || (dc > MAX_DUTY)) {
+			prescale++;
+			if (prescale > MAX_PRESCALE) {
+				ret = -EINVAL;
+				goto err;
+			}
+			continue;
+		}
+		if ((pv < MIN_PERIOD) || (dc < MIN_DUTY)) {
+			ret = -EINVAL;
+			goto err;
+		}
+		break;
+	}
+
+	/*
+	 * NOTE: the clock to PWM has to be enabled first
+	 * before writing to the registers
+	 */
+	spin_lock(&pwmd->pwm->lock);
+	ret = clk_enable(pwmd->pwm->clk);
+	if (ret) {
+		spin_unlock(&pwmd->pwm->lock);
+		goto err;
+	}
+
+	spin_lock(&pwmd->lock);
+	writel(prescale << PRESCALE_SHIFT, pwmd->pwm->mmio_base +
+			pwmd->offset + PWMCR);
+	writel(dc, pwmd->pwm->mmio_base + pwmd->offset + PWMDCR);
+	writel(pv, pwmd->pwm->mmio_base + pwmd->offset + PWMPCR);
+	spin_unlock(&pwmd->lock);
+	clk_disable(pwmd->pwm->clk);
+	spin_unlock(&pwmd->pwm->lock);
+
+	return 0;
+err:
+	dev_err(&pwmd->pwm->pdev->dev, "pwm config fail\n");
+	return ret;
+}
+EXPORT_SYMBOL(pwm_config);
+
+int pwm_enable(struct pwm_device *pwmd)
+{
+	int ret = 0;
+	u32 val = 0;
+
+	if (!pwmd) {
+		pr_err("pwm: enable - NULL pwm device pointer\n");
+		return -EFAULT;
+	}
+
+	spin_lock(&pwmd->pwm->lock);
+	ret = clk_enable(pwmd->pwm->clk);
+	if (!ret)
+		pwmd->pwm->clk_enabled++;
+	else {
+		spin_unlock(&pwmd->pwm->lock);
+		goto err;
+	}
+
+	spin_lock(&pwmd->lock);
+	val = readl(pwmd->pwm->mmio_base + pwmd->offset + PWMCR);
+	writel(val | PWM_EN_MASK, pwmd->pwm->mmio_base + pwmd->offset + PWMCR);
+	spin_unlock(&pwmd->lock);
+	spin_unlock(&pwmd->pwm->lock);
+	return 0;
+err:
+	dev_err(&pwmd->pwm->pdev->dev, "pwm enable fail\n");
+	return ret;
+}
+EXPORT_SYMBOL(pwm_enable);
+
+void pwm_disable(struct pwm_device *pwmd)
+{
+	if (!pwmd) {
+		pr_err("pwm: disable - NULL pwm device pointer\n");
+		return;
+	}
+
+	spin_lock(&pwmd->pwm->lock);
+	spin_lock(&pwmd->lock);
+	writel(0, pwmd->pwm->mmio_base + pwmd->offset + PWMCR);
+	if (pwmd->pwm->clk_enabled) {
+		clk_disable(pwmd->pwm->clk);
+		pwmd->pwm->clk_enabled--;
+	}
+	spin_unlock(&pwmd->lock);
+	spin_unlock(&pwmd->pwm->lock);
+}
+EXPORT_SYMBOL(pwm_disable);
+
+struct pwm_device *pwm_request(int pwmd_id, const char *label)
+{
+	int found = 0;
+	struct pwm *pwm;
+	struct pwm_device *pwmd = NULL;
+
+	spin_lock(&list_lock);
+	list_for_each_entry(pwm, &pwm_list, node) {
+		spin_lock(&pwm->lock);
+		list_for_each_entry(pwmd, &pwm->devices, node) {
+			if (pwmd->pwmd_id == pwmd_id) {
+				found = 1;
+				break;
+			}
+		}
+		spin_unlock(&pwm->lock);
+		if (found)
+			break;
+	}
+	spin_unlock(&list_lock);
+
+	if (found) {
+		spin_lock(&pwmd->lock);
+		if (pwmd->busy == 0) {
+			pwmd->busy++;
+			pwmd->label = label;
+		} else
+			pwmd = ERR_PTR(-EBUSY);
+		spin_unlock(&pwmd->lock);
+	} else
+		pwmd = ERR_PTR(-ENOENT);
+
+	if (IS_ERR(pwmd))
+		pr_err("pwm: request fail\n");
+
+	return pwmd;
+}
+EXPORT_SYMBOL(pwm_request);
+
+void pwm_free(struct pwm_device *pwmd)
+{
+	if (!pwmd) {
+		pr_err("pwm: disable - NULL pwm device pointer\n");
+		return;
+	}
+
+	spin_lock(&pwmd->lock);
+	if (pwmd->busy) {
+		pwmd->busy--;
+		pwmd->label = NULL;
+	} else {
+		spin_unlock(&pwmd->lock);
+		dev_warn(&pwmd->pwm->pdev->dev, "pwm device already freed\n");
+		return;
+	}
+
+	spin_unlock(&pwmd->lock);
+}
+EXPORT_SYMBOL(pwm_free);
+
+/* creates and add pwmd device to parent pwm's devices list */
+static int add_pwm_device(unsigned int pwmd_id, struct pwm *pwm)
+{
+	struct pwm_device *pwmd;
+
+	pwmd = kzalloc(sizeof(*pwmd), GFP_KERNEL);
+	if (!pwmd)
+		return -ENOMEM;
+
+	pwmd->pwm = pwm;
+	pwmd->busy = 0;
+	pwmd->pwmd_id = pwmd_id + pwm->id * PWM_DEVICE_PER_IP;
+	pwmd->offset = pwmd_id * PWM_DEVICE_OFFSET;
+	spin_lock_init(&pwmd->lock);
+
+	spin_lock(&pwm->lock);
+	list_add_tail(&pwmd->node, &pwm->devices);
+	spin_unlock(&pwm->lock);
+
+	return 0;
+}
+
+/* removes all pwmd devices from parent pwm's devices list */
+static void remove_pwm_devices(struct pwm *pwm)
+{
+	struct pwm_device *pwmd;
+
+	spin_lock(&pwm->lock);
+	list_for_each_entry(pwmd, &pwm->devices, node) {
+		list_del(&pwmd->node);
+		kfree(pwmd);
+	}
+	spin_unlock(&pwm->lock);
+}
+
+static int __devinit spear_pwm_probe(struct platform_device *pdev)
+{
+	struct pwm *pwm = NULL;
+	struct resource *res;
+	int ret = 0, pwmd_id = 0;
+
+	pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
+	if (!pwm) {
+		ret = -ENOMEM;
+		dev_dbg(&pdev->dev, "failed to allocate memory\n");
+		goto err;
+	}
+
+	pwm->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(pwm->clk)) {
+		ret = PTR_ERR(pwm->clk);
+		dev_dbg(&pdev->dev, "Error getting clock\n");
+		goto err_free;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		ret = -ENODEV;
+		dev_dbg(&pdev->dev, "no memory resource defined\n");
+		goto err_free_clk;
+	}
+
+	if (!request_mem_region(res->start, resource_size(res), pdev->name)) {
+		ret = -EBUSY;
+		dev_dbg(&pdev->dev, "failed to request memory resource\n");
+		goto err_free_clk;
+	}
+
+	pwm->mmio_base = ioremap(res->start, resource_size(res));
+	if (!pwm->mmio_base) {
+		ret = -ENOMEM;
+		dev_dbg(&pdev->dev, "failed to ioremap\n");
+		goto err_free_mem;
+	}
+
+	/* initialize pwm structure */
+	pwm->clk_enabled = 0;
+	pwm->pdev = pdev;
+	/* if pdev->id is -1, only one pwm ip is present */
+	if (pdev->id == -1)
+		pwm->id = 0;
+	else
+		pwm->id = pdev->id;
+
+	spin_lock_init(&pwm->lock);
+	INIT_LIST_HEAD(&pwm->devices);
+	platform_set_drvdata(pdev, pwm);
+
+	/* add pwm to pwm list */
+	spin_lock(&list_lock);
+	list_add_tail(&pwm->node, &pwm_list);
+	spin_unlock(&list_lock);
+
+	/* add pwm devices */
+	for (pwmd_id = 0; pwmd_id < PWM_DEVICE_PER_IP; pwmd_id++) {
+		ret = add_pwm_device(pwmd_id, pwm);
+		if (!ret)
+			continue;
+		dev_err(&pdev->dev, "Add device fail for pwm device id: %d\n",
+				pwmd_id);
+	}
+
+	if (list_empty(&pwm->node))
+		goto err_remove_pwm;
+
+	dev_info(&pdev->dev, "Initialization successful\n");
+	return 0;
+
+err_remove_pwm:
+	spin_lock(&list_lock);
+	list_del(&pwm->node);
+	spin_unlock(&list_lock);
+
+	platform_set_drvdata(pdev, NULL);
+	iounmap(pwm->mmio_base);
+err_free_mem:
+	release_mem_region(res->start, resource_size(res));
+err_free_clk:
+	clk_put(pwm->clk);
+err_free:
+	kfree(pwm);
+err:
+	dev_err(&pdev->dev, "Initialization Fail. Error: %d\n", ret);
+
+	return ret;
+}
+
+static int __devexit spear_pwm_remove(struct platform_device *pdev)
+{
+	struct pwm *pwm;
+	struct resource *res;
+	int ret = 0;
+
+	pwm = platform_get_drvdata(pdev);
+	if (pwm == NULL) {
+		ret = -ENODEV;
+		dev_dbg(&pdev->dev, "Remove: get_drvdata fail\n");
+		goto err;
+	}
+	platform_set_drvdata(pdev, NULL);
+
+	/* remove pwm devices */
+	remove_pwm_devices(pwm);
+
+	/* remove pwm from pwm_list */
+	spin_lock(&list_lock);
+	list_del(&pwm->node);
+	spin_unlock(&list_lock);
+
+	iounmap(pwm->mmio_base);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		ret = -ENODEV;
+		dev_dbg(&pdev->dev, "Remove: get_resource fail\n");
+		goto err;
+	}
+	release_mem_region(res->start, resource_size(res));
+
+	if (pwm->clk_enabled)
+		clk_disable(pwm->clk);
+	clk_put(pwm->clk);
+
+	kfree(pwm);
+	return 0;
+
+err:
+	dev_err(&pdev->dev, "Remove: Fail - %d\n", ret);
+	return ret;
+}
+
+static struct platform_driver spear_pwm_driver = {
+	.driver = {
+		.name = "pwm",
+		.bus = &platform_bus_type,
+		.owner = THIS_MODULE,
+	},
+	.probe = spear_pwm_probe,
+	.remove = __devexit_p(spear_pwm_remove)
+};
+
+static int __init spear_pwm_init(void)
+{
+	int ret = 0;
+
+	ret = platform_driver_register(&spear_pwm_driver);
+	if (ret)
+		pr_err("failed to register spear_pwm_driver\n");
+
+	return ret;
+}
+module_init(spear_pwm_init);
+
+static void __exit spear_pwm_exit(void)
+{
+	platform_driver_unregister(&spear_pwm_driver);
+}
+module_exit(spear_pwm_exit);
+
+MODULE_AUTHOR("Viresh Kumar");
+MODULE_DESCRIPTION("SPEAr PWM Driver");
+MODULE_LICENSE("GPL");