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Linux/drivers/pwm/pwm-puv3.c

  1 /*
  2  * linux/arch/unicore32/kernel/pwm.c
  3  *
  4  * Code specific to PKUnity SoC and UniCore ISA
  5  *
  6  *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
  7  *      Copyright (C) 2001-2010 Guan Xuetao
  8  *
  9  * This program is free software; you can redistribute it and/or modify
 10  * it under the terms of the GNU General Public License version 2 as
 11  * published by the Free Software Foundation.
 12  */
 13 
 14 #include <linux/module.h>
 15 #include <linux/kernel.h>
 16 #include <linux/platform_device.h>
 17 #include <linux/slab.h>
 18 #include <linux/err.h>
 19 #include <linux/clk.h>
 20 #include <linux/io.h>
 21 #include <linux/pwm.h>
 22 
 23 #include <asm/div64.h>
 24 #include <mach/hardware.h>
 25 
 26 struct puv3_pwm_chip {
 27         struct pwm_chip chip;
 28         void __iomem *base;
 29         struct clk *clk;
 30 };
 31 
 32 static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
 33 {
 34         return container_of(chip, struct puv3_pwm_chip, chip);
 35 }
 36 
 37 /*
 38  * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
 39  * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 40  */
 41 static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 42                            int duty_ns, int period_ns)
 43 {
 44         unsigned long period_cycles, prescale, pv, dc;
 45         struct puv3_pwm_chip *puv3 = to_puv3(chip);
 46         unsigned long long c;
 47 
 48         c = clk_get_rate(puv3->clk);
 49         c = c * period_ns;
 50         do_div(c, 1000000000);
 51         period_cycles = c;
 52 
 53         if (period_cycles < 1)
 54                 period_cycles = 1;
 55 
 56         prescale = (period_cycles - 1) / 1024;
 57         pv = period_cycles / (prescale + 1) - 1;
 58 
 59         if (prescale > 63)
 60                 return -EINVAL;
 61 
 62         if (duty_ns == period_ns)
 63                 dc = OST_PWMDCCR_FDCYCLE;
 64         else
 65                 dc = (pv + 1) * duty_ns / period_ns;
 66 
 67         /*
 68          * NOTE: the clock to PWM has to be enabled first
 69          * before writing to the registers
 70          */
 71         clk_prepare_enable(puv3->clk);
 72 
 73         writel(prescale, puv3->base + OST_PWM_PWCR);
 74         writel(pv - dc, puv3->base + OST_PWM_DCCR);
 75         writel(pv, puv3->base + OST_PWM_PCR);
 76 
 77         clk_disable_unprepare(puv3->clk);
 78 
 79         return 0;
 80 }
 81 
 82 static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 83 {
 84         struct puv3_pwm_chip *puv3 = to_puv3(chip);
 85 
 86         return clk_prepare_enable(puv3->clk);
 87 }
 88 
 89 static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 90 {
 91         struct puv3_pwm_chip *puv3 = to_puv3(chip);
 92 
 93         clk_disable_unprepare(puv3->clk);
 94 }
 95 
 96 static const struct pwm_ops puv3_pwm_ops = {
 97         .config = puv3_pwm_config,
 98         .enable = puv3_pwm_enable,
 99         .disable = puv3_pwm_disable,
100         .owner = THIS_MODULE,
101 };
102 
103 static int pwm_probe(struct platform_device *pdev)
104 {
105         struct puv3_pwm_chip *puv3;
106         struct resource *r;
107         int ret;
108 
109         puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
110         if (puv3 == NULL) {
111                 dev_err(&pdev->dev, "failed to allocate memory\n");
112                 return -ENOMEM;
113         }
114 
115         puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
116         if (IS_ERR(puv3->clk))
117                 return PTR_ERR(puv3->clk);
118 
119         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
120         puv3->base = devm_ioremap_resource(&pdev->dev, r);
121         if (IS_ERR(puv3->base))
122                 return PTR_ERR(puv3->base);
123 
124         puv3->chip.dev = &pdev->dev;
125         puv3->chip.ops = &puv3_pwm_ops;
126         puv3->chip.base = -1;
127         puv3->chip.npwm = 1;
128 
129         ret = pwmchip_add(&puv3->chip);
130         if (ret < 0) {
131                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
132                 return ret;
133         }
134 
135         platform_set_drvdata(pdev, puv3);
136         return 0;
137 }
138 
139 static int pwm_remove(struct platform_device *pdev)
140 {
141         struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
142 
143         return pwmchip_remove(&puv3->chip);
144 }
145 
146 static struct platform_driver puv3_pwm_driver = {
147         .driver = {
148                 .name = "PKUnity-v3-PWM",
149                 .owner = THIS_MODULE,
150         },
151         .probe = pwm_probe,
152         .remove = pwm_remove,
153 };
154 module_platform_driver(puv3_pwm_driver);
155 
156 MODULE_LICENSE("GPL v2");
157 

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