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         offset = pwm->hwpwm ? 0x10 : 0;
  74
  75         c = clk_get_rate(pc->clk);
  76         c = c * period_ns;
  77         do_div(c, 1000000000);
  78         period_cycles = c;
  79
  80         if (period_cycles < 1)
  81                 period_cycles = 1;
  82         prescale = (period_cycles - 1) / 1024;
  83         pv = period_cycles / (prescale + 1) - 1;
  84
  85         if (prescale > 63)
  86                 return -EINVAL;
  87
  88         if (duty_ns == period_ns)
  89                 dc = PWMDCR_FD;
  90         else
  91                 dc = (pv + 1) * duty_ns / period_ns;
  92
  93         /* NOTE: the clock to PWM has to be enabled first
  94          * before writing to the registers
  95          */
  96         rc = clk_prepare_enable(pc->clk);
  97         if (rc < 0)
  98                 return rc;
  99
 100         writel(prescale, pc->mmio_base + offset + PWMCR);
 101         writel(dc, pc->mmio_base + offset + PWMDCR);
 102         writel(pv, pc->mmio_base + offset + PWMPCR);
 103
 104         clk_disable_unprepare(pc->clk);
 105         return 0;
 106 }
 107
 108 static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 109 {
 110         struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
 111         int rc = 0;
 112
 113         if (!pc->clk_enabled) {
 114                 rc = clk_prepare_enable(pc->clk);
 115                 if (!rc)
 116                         pc->clk_enabled++;
 117         }
 118         return rc;
 119 }
 120
 121 static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 122 {
 123         struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
 124
 125         if (pc->clk_enabled) {
 126                 clk_disable_unprepare(pc->clk);
 127                 pc->clk_enabled--;
 128         }
 129 }
 130
 131 static struct pwm_ops pxa_pwm_ops = {
 132         .config = pxa_pwm_config,
 133         .enable = pxa_pwm_enable,
 134         .disable = pxa_pwm_disable,
 135         .owner = THIS_MODULE,
 136 };
 137
 138 static int pwm_probe(struct platform_device *pdev)
 139 {
 140         const struct platform_device_id *id = platform_get_device_id(pdev);
 141         struct pxa_pwm_chip *pwm;
 142         struct resource *r;
 143         int ret = 0;
 144
 145         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 146         if (pwm == NULL) {
 147                 dev_err(&pdev->dev, "failed to allocate memory\n");
 148                 return -ENOMEM;
 149         }
 150
 151         pwm->clk = devm_clk_get(&pdev->dev, NULL);
 152         if (IS_ERR(pwm->clk))
 153                 return PTR_ERR(pwm->clk);
 154
 155         pwm->clk_enabled = 0;
 156
 157         pwm->chip.dev = &pdev->dev;
 158         pwm->chip.ops = &pxa_pwm_ops;
 159         pwm->chip.base = -1;
 160         pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
 161
 162         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 163         if (r == NULL) {
 164                 dev_err(&pdev->dev, "no memory resource defined\n");
 165                 return -ENODEV;
 166         }
 167
 168         pwm->mmio_base = devm_request_and_ioremap(&pdev->dev, r);
 169         if (pwm->mmio_base == NULL)
 170                 return -EADDRNOTAVAIL;
 171
 172         ret = pwmchip_add(&pwm->chip);
 173         if (ret < 0) {
 174                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 175                 return ret;
 176         }
 177
 178         platform_set_drvdata(pdev, pwm);
 179         return 0;
 180 }
 181
 182 static int pwm_remove(struct platform_device *pdev)
 183 {
 184         struct pxa_pwm_chip *chip;
 185
 186         chip = platform_get_drvdata(pdev);
 187         if (chip == NULL)
 188                 return -ENODEV;
 189
 190         return pwmchip_remove(&chip->chip);
 191 }
 192
 193 static struct platform_driver pwm_driver = {
 194         .driver         = {
 195                 .name   = "pxa25x-pwm",
 196                 .owner  = THIS_MODULE,
 197         },
 198         .probe          = pwm_probe,
 199         .remove         = pwm_remove,
 200         .id_table       = pwm_id_table,
 201 };
 202
 203 static int __init pwm_init(void)
 204 {
 205         return platform_driver_register(&pwm_driver);
 206 }
 207 arch_initcall(pwm_init);
 208
 209 static void __exit pwm_exit(void)
 210 {
 211         platform_driver_unregister(&pwm_driver);
 212 }
 213 module_exit(pwm_exit);
 214
 215 MODULE_LICENSE("GPL v2");