320 lines
6.4 KiB
C
320 lines
6.4 KiB
C
/*
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* linux/arch/arm/mach-pxa/pwm.c
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*
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* simple driver for PWM (Pulse Width Modulator) controller
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* 2008-02-13 initial version
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* eric miao <eric.miao@marvell.com>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/err.h>
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/pwm.h>
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#include <asm/div64.h>
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#include <mach/pxa-regs.h>
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/* PWM registers and bits definitions */
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#define PWMCR (0x00)
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#define PWMDCR (0x04)
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#define PWMPCR (0x08)
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#define PWMCR_SD (1 << 6)
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#define PWMDCR_FD (1 << 10)
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struct pwm_device {
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struct list_head node;
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struct platform_device *pdev;
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const char *label;
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struct clk *clk;
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int clk_enabled;
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void __iomem *mmio_base;
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unsigned int use_count;
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unsigned int pwm_id;
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};
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/*
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* period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
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* duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
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*/
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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unsigned long long c;
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unsigned long period_cycles, prescale, pv, dc;
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if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
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return -EINVAL;
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c = clk_get_rate(pwm->clk);
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c = c * period_ns;
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do_div(c, 1000000000);
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period_cycles = c;
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if (period_cycles < 1)
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period_cycles = 1;
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prescale = (period_cycles - 1) / 1024;
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pv = period_cycles / (prescale + 1) - 1;
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if (prescale > 63)
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return -EINVAL;
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if (duty_ns == period_ns)
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dc = PWMDCR_FD;
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else
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dc = (pv + 1) * duty_ns / period_ns;
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/* NOTE: the clock to PWM has to be enabled first
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* before writing to the registers
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*/
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clk_enable(pwm->clk);
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__raw_writel(prescale, pwm->mmio_base + PWMCR);
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__raw_writel(dc, pwm->mmio_base + PWMDCR);
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__raw_writel(pv, pwm->mmio_base + PWMPCR);
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clk_disable(pwm->clk);
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return 0;
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}
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EXPORT_SYMBOL(pwm_config);
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int pwm_enable(struct pwm_device *pwm)
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{
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int rc = 0;
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if (!pwm->clk_enabled) {
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rc = clk_enable(pwm->clk);
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if (!rc)
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pwm->clk_enabled = 1;
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}
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return rc;
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}
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EXPORT_SYMBOL(pwm_enable);
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void pwm_disable(struct pwm_device *pwm)
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{
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if (pwm->clk_enabled) {
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clk_disable(pwm->clk);
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pwm->clk_enabled = 0;
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}
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}
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EXPORT_SYMBOL(pwm_disable);
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static DEFINE_MUTEX(pwm_lock);
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static LIST_HEAD(pwm_list);
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struct pwm_device *pwm_request(int pwm_id, const char *label)
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{
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struct pwm_device *pwm;
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int found = 0;
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mutex_lock(&pwm_lock);
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list_for_each_entry(pwm, &pwm_list, node) {
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if (pwm->pwm_id == pwm_id) {
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found = 1;
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break;
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}
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}
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if (found) {
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if (pwm->use_count == 0) {
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pwm->use_count++;
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pwm->label = label;
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} else
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pwm = ERR_PTR(-EBUSY);
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} else
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pwm = ERR_PTR(-ENOENT);
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mutex_unlock(&pwm_lock);
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return pwm;
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}
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EXPORT_SYMBOL(pwm_request);
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void pwm_free(struct pwm_device *pwm)
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{
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mutex_lock(&pwm_lock);
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if (pwm->use_count) {
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pwm->use_count--;
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pwm->label = NULL;
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} else
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pr_warning("PWM device already freed\n");
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mutex_unlock(&pwm_lock);
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}
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EXPORT_SYMBOL(pwm_free);
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static inline void __add_pwm(struct pwm_device *pwm)
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{
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mutex_lock(&pwm_lock);
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list_add_tail(&pwm->node, &pwm_list);
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mutex_unlock(&pwm_lock);
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}
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static struct pwm_device *pwm_probe(struct platform_device *pdev,
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unsigned int pwm_id, struct pwm_device *parent_pwm)
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{
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struct pwm_device *pwm;
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struct resource *r;
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int ret = 0;
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pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
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if (pwm == NULL) {
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dev_err(&pdev->dev, "failed to allocate memory\n");
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return ERR_PTR(-ENOMEM);
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}
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pwm->clk = clk_get(&pdev->dev, "PWMCLK");
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if (IS_ERR(pwm->clk)) {
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ret = PTR_ERR(pwm->clk);
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goto err_free;
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}
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pwm->clk_enabled = 0;
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pwm->use_count = 0;
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pwm->pwm_id = pwm_id;
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pwm->pdev = pdev;
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if (parent_pwm != NULL) {
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/* registers for the second PWM has offset of 0x10 */
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pwm->mmio_base = parent_pwm->mmio_base + 0x10;
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__add_pwm(pwm);
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return pwm;
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}
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (r == NULL) {
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dev_err(&pdev->dev, "no memory resource defined\n");
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ret = -ENODEV;
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goto err_free_clk;
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}
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r = request_mem_region(r->start, r->end - r->start + 1, pdev->name);
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if (r == NULL) {
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dev_err(&pdev->dev, "failed to request memory resource\n");
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ret = -EBUSY;
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goto err_free_clk;
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}
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pwm->mmio_base = ioremap(r->start, r->end - r->start + 1);
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if (pwm->mmio_base == NULL) {
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dev_err(&pdev->dev, "failed to ioremap() registers\n");
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ret = -ENODEV;
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goto err_free_mem;
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}
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__add_pwm(pwm);
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platform_set_drvdata(pdev, pwm);
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return pwm;
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err_free_mem:
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release_mem_region(r->start, r->end - r->start + 1);
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err_free_clk:
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clk_put(pwm->clk);
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err_free:
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kfree(pwm);
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return ERR_PTR(ret);
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}
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static int __devinit pxa25x_pwm_probe(struct platform_device *pdev)
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{
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struct pwm_device *pwm = pwm_probe(pdev, pdev->id, NULL);
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if (IS_ERR(pwm))
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return PTR_ERR(pwm);
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return 0;
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}
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static int __devinit pxa27x_pwm_probe(struct platform_device *pdev)
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{
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struct pwm_device *pwm;
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pwm = pwm_probe(pdev, pdev->id, NULL);
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if (IS_ERR(pwm))
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return PTR_ERR(pwm);
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pwm = pwm_probe(pdev, pdev->id + 2, pwm);
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if (IS_ERR(pwm))
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return PTR_ERR(pwm);
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return 0;
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}
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static int __devexit pwm_remove(struct platform_device *pdev)
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{
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struct pwm_device *pwm;
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struct resource *r;
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pwm = platform_get_drvdata(pdev);
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if (pwm == NULL)
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return -ENODEV;
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mutex_lock(&pwm_lock);
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list_del(&pwm->node);
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mutex_unlock(&pwm_lock);
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iounmap(pwm->mmio_base);
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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release_mem_region(r->start, r->end - r->start + 1);
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clk_put(pwm->clk);
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kfree(pwm);
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return 0;
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}
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static struct platform_driver pxa25x_pwm_driver = {
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.driver = {
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.name = "pxa25x-pwm",
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},
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.probe = pxa25x_pwm_probe,
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.remove = __devexit_p(pwm_remove),
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};
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static struct platform_driver pxa27x_pwm_driver = {
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.driver = {
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.name = "pxa27x-pwm",
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},
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.probe = pxa27x_pwm_probe,
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.remove = __devexit_p(pwm_remove),
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};
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static int __init pwm_init(void)
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{
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int ret = 0;
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ret = platform_driver_register(&pxa25x_pwm_driver);
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if (ret) {
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printk(KERN_ERR "failed to register pxa25x_pwm_driver\n");
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return ret;
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}
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ret = platform_driver_register(&pxa27x_pwm_driver);
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if (ret) {
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printk(KERN_ERR "failed to register pxa27x_pwm_driver\n");
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return ret;
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}
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return ret;
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}
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arch_initcall(pwm_init);
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static void __exit pwm_exit(void)
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{
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platform_driver_unregister(&pxa25x_pwm_driver);
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platform_driver_unregister(&pxa27x_pwm_driver);
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}
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module_exit(pwm_exit);
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MODULE_LICENSE("GPL v2");
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