drivers/pwm/pwm-pxa.c

   1 /*
   2  * drivers/pwm/pwm-pxa.c
   3  *
   4  * simple driver for PWM (Pulse Width Modulator) controller
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * 2008-02-13   initial version
  11  *              eric miao <eric.miao@marvell.com>
  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
  25 #define HAS_SECONDARY_PWM       0x10
  26
  27 static const struct platform_device_id pwm_id_table[] = {
  28         /*   PWM    has_secondary_pwm? */
  29         { "pxa25x-pwm", 0 },
  30         { "pxa27x-pwm", HAS_SECONDARY_PWM },
  31         { "pxa168-pwm", 0 },
  32         { "pxa910-pwm", 0 },
  33         { },
  34 };
  35 MODULE_DEVICE_TABLE(platform, pwm_id_table);
  36
  37 /* PWM registers and bits definitions */
  38 #define PWMCR           (0x00)
  39 #define PWMDCR          (0x04)
  40 #define PWMPCR          (0x08)
  41
  42 #define PWMCR_SD        (1 << 6)
  43 #define PWMDCR_FD       (1 << 10)
  44
  45 struct pxa_pwm_chip {
  46         struct pwm_chip chip;
  47         struct device   *dev;
  48
  49         struct clk      *clk;
  50         void __iomem    *mmio_base;
  51 };
  52
  53 static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
  54 {
  55         return container_of(chip, struct pxa_pwm_chip, chip);
  56 }
  57
  58 /*
  59  * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
  60  * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
  61  */
  62 static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  63                           int duty_ns, int period_ns)
  64 {
  65         struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
  66         unsigned long long c;
  67         unsigned long period_cycles, prescale, pv, dc;
  68         unsigned long offset;
  69         int rc;
  70
  71         offset = pwm->hwpwm ? 0x10 : 0;
  72
  73         c = clk_get_rate(pc->clk);
  74         c = c * period_ns;
  75         do_div(c, 1000000000);
  76         period_cycles = c;
  77
  78         if (period_cycles < 1)
  79                 period_cycles = 1;
  80         prescale = (period_cycles - 1) / 1024;
  81         pv = period_cycles / (prescale + 1) - 1;
  82
  83         if (prescale > 63)
  84                 return -EINVAL;
  85
  86         if (duty_ns == period_ns)
  87                 dc = PWMDCR_FD;
  88         else
  89                 dc = (pv + 1) * duty_ns / period_ns;
  90
  91         /* NOTE: the clock to PWM has to be enabled first
  92          * before writing to the registers
  93          */
  94         rc = clk_prepare_enable(pc->clk);
  95         if (rc < 0)
  96                 return rc;
  97
  98         writel(prescale, pc->mmio_base + offset + PWMCR);
  99         writel(dc, pc->mmio_base + offset + PWMDCR);
 100         writel(pv, pc->mmio_base + offset + PWMPCR);
 101
 102         clk_disable_unprepare(pc->clk);
 103         return 0;
 104 }
 105
 106 static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 107 {
 108         struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
 109
 110         return clk_prepare_enable(pc->clk);
 111 }
 112
 113 static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 114 {
 115         struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
 116
 117         clk_disable_unprepare(pc->clk);
 118 }
 119
 120 static struct pwm_ops pxa_pwm_ops = {
 121         .config = pxa_pwm_config,
 122         .enable = pxa_pwm_enable,
 123         .disable = pxa_pwm_disable,
 124         .owner = THIS_MODULE,
 125 };
 126
 127 static int pwm_probe(struct platform_device *pdev)
 128 {
 129         const struct platform_device_id *id = platform_get_device_id(pdev);
 130         struct pxa_pwm_chip *pwm;
 131         struct resource *r;
 132         int ret = 0;
 133
 134         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 135         if (pwm == NULL) {
 136                 dev_err(&pdev->dev, "failed to allocate memory\n");
 137                 return -ENOMEM;
 138         }
 139
 140         pwm->clk = devm_clk_get(&pdev->dev, NULL);
 141         if (IS_ERR(pwm->clk))
 142                 return PTR_ERR(pwm->clk);
 143
 144         pwm->chip.dev = &pdev->dev;
 145         pwm->chip.ops = &pxa_pwm_ops;
 146         pwm->chip.base = -1;
 147         pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
 148
 149         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 150         pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
 151         if (IS_ERR(pwm->mmio_base))
 152                 return PTR_ERR(pwm->mmio_base);
 153
 154         ret = pwmchip_add(&pwm->chip);
 155         if (ret < 0) {
 156                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 157                 return ret;
 158         }
 159
 160         platform_set_drvdata(pdev, pwm);
 161         return 0;
 162 }
 163
 164 static int pwm_remove(struct platform_device *pdev)
 165 {
 166         struct pxa_pwm_chip *chip;
 167
 168         chip = platform_get_drvdata(pdev);
 169         if (chip == NULL)
 170                 return -ENODEV;
 171
 172         return pwmchip_remove(&chip->chip);
 173 }
 174
 175 static struct platform_driver pwm_driver = {
 176         .driver         = {
 177                 .name   = "pxa25x-pwm",
 178                 .owner  = THIS_MODULE,
 179         },
 180         .probe          = pwm_probe,
 181         .remove         = pwm_remove,
 182         .id_table       = pwm_id_table,
 183 };
 184
 185 module_platform_driver(pwm_driver);
 186
 187 MODULE_LICENSE("GPL v2");