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