292 lines
6.4 KiB
C
292 lines
6.4 KiB
C
/*
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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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* Derived from pxa PWM driver by 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 <mach/hardware.h>
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/* i.MX1 and i.MX21 share the same PWM function block: */
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#define MX1_PWMC 0x00 /* PWM Control Register */
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#define MX1_PWMS 0x04 /* PWM Sample Register */
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#define MX1_PWMP 0x08 /* PWM Period Register */
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/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
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#define MX3_PWMCR 0x00 /* PWM Control Register */
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#define MX3_PWMSAR 0x0C /* PWM Sample Register */
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#define MX3_PWMPR 0x10 /* PWM Period Register */
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#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
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#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
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#define MX3_PWMCR_CLKSRC_IPG (1 << 16)
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#define MX3_PWMCR_EN (1 << 0)
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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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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
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return -EINVAL;
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if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25()) {
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unsigned long long c;
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unsigned long period_cycles, duty_cycles, prescale;
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u32 cr;
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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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prescale = period_cycles / 0x10000 + 1;
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period_cycles /= prescale;
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c = (unsigned long long)period_cycles * duty_ns;
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do_div(c, period_ns);
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duty_cycles = c;
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writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
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writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
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cr = MX3_PWMCR_PRESCALER(prescale) | MX3_PWMCR_EN;
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if (cpu_is_mx25())
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cr |= MX3_PWMCR_CLKSRC_IPG;
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else
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cr |= MX3_PWMCR_CLKSRC_IPG_HIGH;
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writel(cr, pwm->mmio_base + MX3_PWMCR);
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} else if (cpu_is_mx1() || cpu_is_mx21()) {
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/* The PWM subsystem allows for exact frequencies. However,
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* I cannot connect a scope on my device to the PWM line and
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* thus cannot provide the program the PWM controller
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* exactly. Instead, I'm relying on the fact that the
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* Bootloader (u-boot or WinCE+haret) has programmed the PWM
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* function group already. So I'll just modify the PWM sample
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* register to follow the ratio of duty_ns vs. period_ns
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* accordingly.
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*
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* This is good enough for programming the brightness of
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* the LCD backlight.
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*
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* The real implementation would divide PERCLK[0] first by
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* both the prescaler (/1 .. /128) and then by CLKSEL
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* (/2 .. /16).
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*/
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u32 max = readl(pwm->mmio_base + MX1_PWMP);
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u32 p = max * duty_ns / period_ns;
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writel(max - p, pwm->mmio_base + MX1_PWMS);
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} else {
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BUG();
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}
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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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writel(0, pwm->mmio_base + MX3_PWMCR);
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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 int __devinit mxc_pwm_probe(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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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 -ENOMEM;
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}
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pwm->clk = clk_get(&pdev->dev, "pwm");
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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 = pdev->id;
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pwm->pdev = pdev;
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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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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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platform_set_drvdata(pdev, pwm);
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return 0;
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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 ret;
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}
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static int __devexit mxc_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 mxc_pwm_driver = {
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.driver = {
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.name = "mxc_pwm",
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},
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.probe = mxc_pwm_probe,
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.remove = __devexit_p(mxc_pwm_remove),
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};
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static int __init mxc_pwm_init(void)
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{
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return platform_driver_register(&mxc_pwm_driver);
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}
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arch_initcall(mxc_pwm_init);
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static void __exit mxc_pwm_exit(void)
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{
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platform_driver_unregister(&mxc_pwm_driver);
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}
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module_exit(mxc_pwm_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
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