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 #define PWM_ID_BASE(d)          ((d) & 0xf)
  27
  28 static const struct platform_device_id pwm_id_table[] = {
  29         /*   PWM    has_secondary_pwm? */
  30         { "pxa25x-pwm", 0 },
  31         { "pxa27x-pwm", 0 | HAS_SECONDARY_PWM },
  32         { "pxa168-pwm", 1 },
  33         { "pxa910-pwm", 1 },
  34         { },
  35 };
  36 MODULE_DEVICE_TABLE(platform, pwm_id_table);
  37
  38 /* PWM registers and bits definitions */
  39 #define PWMCR           (0x00)
  40 #define PWMDCR          (0x04)
  41 #define PWMPCR          (0x08)
  42
  43 #define PWMCR_SD        (1 << 6)
  44 #define PWMDCR_FD       (1 << 10)
  45
  46 struct pxa_pwm_chip {
  47         struct pwm_chip chip;
  48         struct device   *dev;
  49
  50         struct clk      *clk;
  51         int             clk_enabled;
  52         void __iomem    *mmio_base;
  53 };
  54
  55 static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
  56 {
  57         return container_of(chip, struct pxa_pwm_chip, chip);
  58 }
  59
  60 /*
  61  * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
  62  * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
  63  */
  64 static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  65                           int duty_ns, int period_ns)
  66 {
  67         struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
  68         unsigned long long c;
  69         unsigned long period_cycles, prescale, pv, dc;
  70         unsigned long offset;
  71         int rc;
  72
  73         if (period_ns == 0 || duty_ns > period_ns)
  74                 return -EINVAL;
  75
  76         offset = pwm->hwpwm ? 0x10 : 0;
  77
  78         c = clk_get_rate(pc->clk);
  79         c = c * period_ns;
  80         do_div(c, 1000000000);
  81         period_cycles = c;
  82
  83         if (period_cycles < 1)
  84                 period_cycles = 1;
  85         prescale = (period_cycles - 1) / 1024;
  86         pv = period_cycles / (prescale + 1) - 1;
  87
  88         if (prescale > 63)
  89                 return -EINVAL;
  90
  91         if (duty_ns == period_ns)
  92                 dc = PWMDCR_FD;
  93         else
  94                 dc = (pv + 1) * duty_ns / period_ns;
  95
  96         /* NOTE: the clock to PWM has to be enabled first
  97          * before writing to the registers
  98          */
  99         rc = clk_prepare_enable(pc->clk);
 100         if (rc < 0)
 101                 return rc;
 102
 103         writel(prescale, pc->mmio_base + offset + PWMCR);
 104         writel(dc, pc->mmio_base + offset + PWMDCR);
 105         writel(pv, pc->mmio_base + offset + PWMPCR);
 106
 107         clk_disable_unprepare(pc->clk);
 108         return 0;
 109 }
 110
 111 static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 112 {
 113         struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
 114         int rc = 0;
 115
 116         if (!pc->clk_enabled) {
 117                 rc = clk_prepare_enable(pc->clk);
 118                 if (!rc)
 119                         pc->clk_enabled++;
 120         }
 121         return rc;
 122 }
 123
 124 static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 125 {
 126         struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
 127
 128         if (pc->clk_enabled) {
 129                 clk_disable_unprepare(pc->clk);
 130                 pc->clk_enabled--;
 131         }
 132 }
 133
 134 static struct pwm_ops pxa_pwm_ops = {
 135         .config = pxa_pwm_config,
 136         .enable = pxa_pwm_enable,
 137         .disable = pxa_pwm_disable,
 138         .owner = THIS_MODULE,
 139 };
 140
 141 static int __devinit pwm_probe(struct platform_device *pdev)
 142 {
 143         const struct platform_device_id *id = platform_get_device_id(pdev);
 144         struct pxa_pwm_chip *pwm;
 145         struct resource *r;
 146         int ret = 0;
 147
 148         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 149         if (pwm == NULL) {
 150                 dev_err(&pdev->dev, "failed to allocate memory\n");
 151                 return -ENOMEM;
 152         }
 153
 154         pwm->clk = devm_clk_get(&pdev->dev, NULL);
 155         if (IS_ERR(pwm->clk))
 156                 return PTR_ERR(pwm->clk);
 157
 158         pwm->clk_enabled = 0;
 159
 160         pwm->chip.dev = &pdev->dev;
 161         pwm->chip.ops = &pxa_pwm_ops;
 162         pwm->chip.base = -1;
 163         pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
 164
 165         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 166         if (r == NULL) {
 167                 dev_err(&pdev->dev, "no memory resource defined\n");
 168                 return -ENODEV;
 169         }
 170
 171         pwm->mmio_base = devm_request_and_ioremap(&pdev->dev, r);
 172         if (pwm->mmio_base == NULL)
 173                 return -EADDRNOTAVAIL;
 174
 175         ret = pwmchip_add(&pwm->chip);
 176         if (ret < 0) {
 177                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 178                 return ret;
 179         }
 180
 181         platform_set_drvdata(pdev, pwm);
 182         return 0;
 183 }
 184
 185 static int __devexit pwm_remove(struct platform_device *pdev)
 186 {
 187         struct pxa_pwm_chip *chip;
 188
 189         chip = platform_get_drvdata(pdev);
 190         if (chip == NULL)
 191                 return -ENODEV;
 192
 193         return pwmchip_remove(&chip->chip);
 194 }
 195
 196 static struct platform_driver pwm_driver = {
 197         .driver         = {
 198                 .name   = "pxa25x-pwm",
 199                 .owner  = THIS_MODULE,
 200         },
 201         .probe          = pwm_probe,
 202         .remove         = __devexit_p(pwm_remove),
 203         .id_table       = pwm_id_table,
 204 };
 205
 206 static int __init pwm_init(void)
 207 {
 208         return platform_driver_register(&pwm_driver);
 209 }
 210 arch_initcall(pwm_init);
 211
 212 static void __exit pwm_exit(void)
 213 {
 214         platform_driver_unregister(&pwm_driver);
 215 }
 216 module_exit(pwm_exit);
 217
 218 MODULE_LICENSE("GPL v2");