arch/arm/plat-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/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 pwm_device {
  47         struct list_head        node;
  48         struct pwm_device       *secondary;
  49         struct platform_device  *pdev;
  50
  51         const char      *label;
  52         struct clk      *clk;
  53         int             clk_enabled;
  54         void __iomem    *mmio_base;
  55
  56         unsigned int    use_count;
  57         unsigned int    pwm_id;
  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 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  65 {
  66         unsigned long long c;
  67         unsigned long period_cycles, prescale, pv, dc;
  68
  69         if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
  70                 return -EINVAL;
  71
  72         c = clk_get_rate(pwm->clk);
  73         c = c * period_ns;
  74         do_div(c, 1000000000);
  75         period_cycles = c;
  76
  77         if (period_cycles < 1)
  78                 period_cycles = 1;
  79         prescale = (period_cycles - 1) / 1024;
  80         pv = period_cycles / (prescale + 1) - 1;
  81
  82         if (prescale > 63)
  83                 return -EINVAL;
  84
  85         if (duty_ns == period_ns)
  86                 dc = PWMDCR_FD;
  87         else
  88                 dc = (pv + 1) * duty_ns / period_ns;
  89
  90         /* NOTE: the clock to PWM has to be enabled first
  91          * before writing to the registers
  92          */
  93         clk_enable(pwm->clk);
  94         __raw_writel(prescale, pwm->mmio_base + PWMCR);
  95         __raw_writel(dc, pwm->mmio_base + PWMDCR);
  96         __raw_writel(pv, pwm->mmio_base + PWMPCR);
  97         clk_disable(pwm->clk);
  98
  99         return 0;
 100 }
 101 EXPORT_SYMBOL(pwm_config);
 102
 103 int pwm_enable(struct pwm_device *pwm)
 104 {
 105         int rc = 0;
 106
 107         if (!pwm->clk_enabled) {
 108                 rc = clk_enable(pwm->clk);
 109                 if (!rc)
 110                         pwm->clk_enabled = 1;
 111         }
 112         return rc;
 113 }
 114 EXPORT_SYMBOL(pwm_enable);
 115
 116 void pwm_disable(struct pwm_device *pwm)
 117 {
 118         if (pwm->clk_enabled) {
 119                 clk_disable(pwm->clk);
 120                 pwm->clk_enabled = 0;
 121         }
 122 }
 123 EXPORT_SYMBOL(pwm_disable);
 124
 125 static DEFINE_MUTEX(pwm_lock);
 126 static LIST_HEAD(pwm_list);
 127
 128 struct pwm_device *pwm_request(int pwm_id, const char *label)
 129 {
 130         struct pwm_device *pwm;
 131         int found = 0;
 132
 133         mutex_lock(&pwm_lock);
 134
 135         list_for_each_entry(pwm, &pwm_list, node) {
 136                 if (pwm->pwm_id == pwm_id) {
 137                         found = 1;
 138                         break;
 139                 }
 140         }
 141
 142         if (found) {
 143                 if (pwm->use_count == 0) {
 144                         pwm->use_count++;
 145                         pwm->label = label;
 146                 } else
 147                         pwm = ERR_PTR(-EBUSY);
 148         } else
 149                 pwm = ERR_PTR(-ENOENT);
 150
 151         mutex_unlock(&pwm_lock);
 152         return pwm;
 153 }
 154 EXPORT_SYMBOL(pwm_request);
 155
 156 void pwm_free(struct pwm_device *pwm)
 157 {
 158         mutex_lock(&pwm_lock);
 159
 160         if (pwm->use_count) {
 161                 pwm->use_count--;
 162                 pwm->label = NULL;
 163         } else
 164                 pr_warning("PWM device already freed\n");
 165
 166         mutex_unlock(&pwm_lock);
 167 }
 168 EXPORT_SYMBOL(pwm_free);
 169
 170 static inline void __add_pwm(struct pwm_device *pwm)
 171 {
 172         mutex_lock(&pwm_lock);
 173         list_add_tail(&pwm->node, &pwm_list);
 174         mutex_unlock(&pwm_lock);
 175 }
 176
 177 static int __devinit pwm_probe(struct platform_device *pdev)
 178 {
 179         struct platform_device_id *id = platform_get_device_id(pdev);
 180         struct pwm_device *pwm, *secondary = NULL;
 181         struct resource *r;
 182         int ret = 0;
 183
 184         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 185         if (pwm == NULL) {
 186                 dev_err(&pdev->dev, "failed to allocate memory\n");
 187                 return -ENOMEM;
 188         }
 189
 190         pwm->clk = clk_get(&pdev->dev, NULL);
 191         if (IS_ERR(pwm->clk)) {
 192                 ret = PTR_ERR(pwm->clk);
 193                 goto err_free;
 194         }
 195         pwm->clk_enabled = 0;
 196
 197         pwm->use_count = 0;
 198         pwm->pwm_id = PWM_ID_BASE(id->driver_data) + pdev->id;
 199         pwm->pdev = pdev;
 200
 201         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 202         if (r == NULL) {
 203                 dev_err(&pdev->dev, "no memory resource defined\n");
 204                 ret = -ENODEV;
 205                 goto err_free_clk;
 206         }
 207
 208         r = request_mem_region(r->start, resource_size(r), pdev->name);
 209         if (r == NULL) {
 210                 dev_err(&pdev->dev, "failed to request memory resource\n");
 211                 ret = -EBUSY;
 212                 goto err_free_clk;
 213         }
 214
 215         pwm->mmio_base = ioremap(r->start, resource_size(r));
 216         if (pwm->mmio_base == NULL) {
 217                 dev_err(&pdev->dev, "failed to ioremap() registers\n");
 218                 ret = -ENODEV;
 219                 goto err_free_mem;
 220         }
 221
 222         if (id->driver_data & HAS_SECONDARY_PWM) {
 223                 secondary = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 224                 if (secondary == NULL) {
 225                         ret = -ENOMEM;
 226                         goto err_free_mem;
 227                 }
 228
 229                 *secondary = *pwm;
 230                 pwm->secondary = secondary;
 231
 232                 /* registers for the second PWM has offset of 0x10 */
 233                 secondary->mmio_base = pwm->mmio_base + 0x10;
 234                 secondary->pwm_id = pdev->id + 2;
 235         }
 236
 237         __add_pwm(pwm);
 238         if (secondary)
 239                 __add_pwm(secondary);
 240
 241         platform_set_drvdata(pdev, pwm);
 242         return 0;
 243
 244 err_free_mem:
 245         release_mem_region(r->start, resource_size(r));
 246 err_free_clk:
 247         clk_put(pwm->clk);
 248 err_free:
 249         kfree(pwm);
 250         return ret;
 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
 264         if (pwm->secondary) {
 265                 list_del(&pwm->secondary->node);
 266                 kfree(pwm->secondary);
 267         }
 268
 269         list_del(&pwm->node);
 270         mutex_unlock(&pwm_lock);
 271
 272         iounmap(pwm->mmio_base);
 273
 274         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 275         release_mem_region(r->start, resource_size(r));
 276
 277         clk_put(pwm->clk);
 278         kfree(pwm);
 279         return 0;
 280 }
 281
 282 static struct platform_driver pwm_driver = {
 283         .driver         = {
 284                 .name   = "pxa25x-pwm",
 285                 .owner  = THIS_MODULE,
 286         },
 287         .probe          = pwm_probe,
 288         .remove         = __devexit_p(pwm_remove),
 289         .id_table       = pwm_id_table,
 290 };
 291
 292 static int __init pwm_init(void)
 293 {
 294         return platform_driver_register(&pwm_driver);
 295 }
 296 arch_initcall(pwm_init);
 297
 298 static void __exit pwm_exit(void)
 299 {
 300         platform_driver_unregister(&pwm_driver);
 301 }
 302 module_exit(pwm_exit);
 303
 304 MODULE_LICENSE("GPL v2");