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