arch/arm/mach-pxa/pwm.c

   1 /*
   2  * linux/arch/arm/mach-pxa/pwm.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/err.h>
  18 #include <linux/clk.h>
  19 #include <linux/io.h>
  20 #include <linux/pwm.h>
  21
  22 #include <asm/div64.h>
  23 #include <mach/pxa-regs.h>
  24
  25 /* PWM registers and bits definitions */
  26 #define PWMCR           (0x00)
  27 #define PWMDCR          (0x04)
  28 #define PWMPCR          (0x08)
  29
  30 #define PWMCR_SD        (1 << 6)
  31 #define PWMDCR_FD       (1 << 10)
  32
  33 struct pwm_device {
  34         struct list_head        node;
  35         struct platform_device *pdev;
  36
  37         const char      *label;
  38         struct clk      *clk;
  39         int             clk_enabled;
  40         void __iomem    *mmio_base;
  41
  42         unsigned int    use_count;
  43         unsigned int    pwm_id;
  44 };
  45
  46 /*
  47  * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
  48  * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
  49  */
  50 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  51 {
  52         unsigned long long c;
  53         unsigned long period_cycles, prescale, pv, dc;
  54
  55         if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
  56                 return -EINVAL;
  57
  58         c = clk_get_rate(pwm->clk);
  59         c = c * period_ns;
  60         do_div(c, 1000000000);
  61         period_cycles = c;
  62
  63         if (period_cycles < 1)
  64                 period_cycles = 1;
  65         prescale = (period_cycles - 1) / 1024;
  66         pv = period_cycles / (prescale + 1) - 1;
  67
  68         if (prescale > 63)
  69                 return -EINVAL;
  70
  71         if (duty_ns == period_ns)
  72                 dc = PWMDCR_FD;
  73         else
  74                 dc = (pv + 1) * duty_ns / period_ns;
  75
  76         /* NOTE: the clock to PWM has to be enabled first
  77          * before writing to the registers
  78          */
  79         clk_enable(pwm->clk);
  80         __raw_writel(prescale, pwm->mmio_base + PWMCR);
  81         __raw_writel(dc, pwm->mmio_base + PWMDCR);
  82         __raw_writel(pv, pwm->mmio_base + PWMPCR);
  83         clk_disable(pwm->clk);
  84
  85         return 0;
  86 }
  87 EXPORT_SYMBOL(pwm_config);
  88
  89 int pwm_enable(struct pwm_device *pwm)
  90 {
  91         int rc = 0;
  92
  93         if (!pwm->clk_enabled) {
  94                 rc = clk_enable(pwm->clk);
  95                 if (!rc)
  96                         pwm->clk_enabled = 1;
  97         }
  98         return rc;
  99 }
 100 EXPORT_SYMBOL(pwm_enable);
 101
 102 void pwm_disable(struct pwm_device *pwm)
 103 {
 104         if (pwm->clk_enabled) {
 105                 clk_disable(pwm->clk);
 106                 pwm->clk_enabled = 0;
 107         }
 108 }
 109 EXPORT_SYMBOL(pwm_disable);
 110
 111 static DEFINE_MUTEX(pwm_lock);
 112 static LIST_HEAD(pwm_list);
 113
 114 struct pwm_device *pwm_request(int pwm_id, const char *label)
 115 {
 116         struct pwm_device *pwm;
 117         int found = 0;
 118
 119         mutex_lock(&pwm_lock);
 120
 121         list_for_each_entry(pwm, &pwm_list, node) {
 122                 if (pwm->pwm_id == pwm_id) {
 123                         found = 1;
 124                         break;
 125                 }
 126         }
 127
 128         if (found) {
 129                 if (pwm->use_count == 0) {
 130                         pwm->use_count++;
 131                         pwm->label = label;
 132                 } else
 133                         pwm = ERR_PTR(-EBUSY);
 134         } else
 135                 pwm = ERR_PTR(-ENOENT);
 136
 137         mutex_unlock(&pwm_lock);
 138         return pwm;
 139 }
 140 EXPORT_SYMBOL(pwm_request);
 141
 142 void pwm_free(struct pwm_device *pwm)
 143 {
 144         mutex_lock(&pwm_lock);
 145
 146         if (pwm->use_count) {
 147                 pwm->use_count--;
 148                 pwm->label = NULL;
 149         } else
 150                 pr_warning("PWM device already freed\n");
 151
 152         mutex_unlock(&pwm_lock);
 153 }
 154 EXPORT_SYMBOL(pwm_free);
 155
 156 static inline void __add_pwm(struct pwm_device *pwm)
 157 {
 158         mutex_lock(&pwm_lock);
 159         list_add_tail(&pwm->node, &pwm_list);
 160         mutex_unlock(&pwm_lock);
 161 }
 162
 163 static struct pwm_device *pwm_probe(struct platform_device *pdev,
 164                 unsigned int pwm_id, struct pwm_device *parent_pwm)
 165 {
 166         struct pwm_device *pwm;
 167         struct resource *r;
 168         int ret = 0;
 169
 170         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 171         if (pwm == NULL) {
 172                 dev_err(&pdev->dev, "failed to allocate memory\n");
 173                 return ERR_PTR(-ENOMEM);
 174         }
 175
 176         pwm->clk = clk_get(&pdev->dev, NULL);
 177         if (IS_ERR(pwm->clk)) {
 178                 ret = PTR_ERR(pwm->clk);
 179                 goto err_free;
 180         }
 181         pwm->clk_enabled = 0;
 182
 183         pwm->use_count = 0;
 184         pwm->pwm_id = pwm_id;
 185         pwm->pdev = pdev;
 186
 187         if (parent_pwm != NULL) {
 188                 /* registers for the second PWM has offset of 0x10 */
 189                 pwm->mmio_base = parent_pwm->mmio_base + 0x10;
 190                 __add_pwm(pwm);
 191                 return pwm;
 192         }
 193
 194         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 195         if (r == NULL) {
 196                 dev_err(&pdev->dev, "no memory resource defined\n");
 197                 ret = -ENODEV;
 198                 goto err_free_clk;
 199         }
 200
 201         r = request_mem_region(r->start, r->end - r->start + 1, pdev->name);
 202         if (r == NULL) {
 203                 dev_err(&pdev->dev, "failed to request memory resource\n");
 204                 ret = -EBUSY;
 205                 goto err_free_clk;
 206         }
 207
 208         pwm->mmio_base = ioremap(r->start, r->end - r->start + 1);
 209         if (pwm->mmio_base == NULL) {
 210                 dev_err(&pdev->dev, "failed to ioremap() registers\n");
 211                 ret = -ENODEV;
 212                 goto err_free_mem;
 213         }
 214
 215         __add_pwm(pwm);
 216         platform_set_drvdata(pdev, pwm);
 217         return pwm;
 218
 219 err_free_mem:
 220         release_mem_region(r->start, r->end - r->start + 1);
 221 err_free_clk:
 222         clk_put(pwm->clk);
 223 err_free:
 224         kfree(pwm);
 225         return ERR_PTR(ret);
 226 }
 227
 228 static int __devinit pxa25x_pwm_probe(struct platform_device *pdev)
 229 {
 230         struct pwm_device *pwm = pwm_probe(pdev, pdev->id, NULL);
 231
 232         if (IS_ERR(pwm))
 233                 return PTR_ERR(pwm);
 234
 235         return 0;
 236 }
 237
 238 static int __devinit pxa27x_pwm_probe(struct platform_device *pdev)
 239 {
 240         struct pwm_device *pwm;
 241
 242         pwm = pwm_probe(pdev, pdev->id, NULL);
 243         if (IS_ERR(pwm))
 244                 return PTR_ERR(pwm);
 245
 246         pwm = pwm_probe(pdev, pdev->id + 2, pwm);
 247         if (IS_ERR(pwm))
 248                 return PTR_ERR(pwm);
 249
 250         return 0;
 251 }
 252
 253 static int __devexit pwm_remove(struct platform_device *pdev)
 254 {
 255         struct pwm_device *pwm;
 256         struct resource *r;
 257
 258         pwm = platform_get_drvdata(pdev);
 259         if (pwm == NULL)
 260                 return -ENODEV;
 261
 262         mutex_lock(&pwm_lock);
 263         list_del(&pwm->node);
 264         mutex_unlock(&pwm_lock);
 265
 266         iounmap(pwm->mmio_base);
 267
 268         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 269         release_mem_region(r->start, r->end - r->start + 1);
 270
 271         clk_put(pwm->clk);
 272         kfree(pwm);
 273         return 0;
 274 }
 275
 276 static struct platform_driver pxa25x_pwm_driver = {
 277         .driver         = {
 278                 .name   = "pxa25x-pwm",
 279         },
 280         .probe          = pxa25x_pwm_probe,
 281         .remove         = __devexit_p(pwm_remove),
 282 };
 283
 284 static struct platform_driver pxa27x_pwm_driver = {
 285         .driver         = {
 286                 .name   = "pxa27x-pwm",
 287         },
 288         .probe          = pxa27x_pwm_probe,
 289         .remove         = __devexit_p(pwm_remove),
 290 };
 291
 292 static int __init pwm_init(void)
 293 {
 294         int ret = 0;
 295
 296         ret = platform_driver_register(&pxa25x_pwm_driver);
 297         if (ret) {
 298                 printk(KERN_ERR "failed to register pxa25x_pwm_driver\n");
 299                 return ret;
 300         }
 301
 302         ret = platform_driver_register(&pxa27x_pwm_driver);
 303         if (ret) {
 304                 printk(KERN_ERR "failed to register pxa27x_pwm_driver\n");
 305                 return ret;
 306         }
 307
 308         return ret;
 309 }
 310 arch_initcall(pwm_init);
 311
 312 static void __exit pwm_exit(void)
 313 {
 314         platform_driver_unregister(&pxa25x_pwm_driver);
 315         platform_driver_unregister(&pxa27x_pwm_driver);
 316 }
 317 module_exit(pwm_exit);
 318
 319 MODULE_LICENSE("GPL v2");