arch/unicore32/kernel/pwm.c

   1 /*
   2  * linux/arch/unicore32/kernel/pwm.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   7  *      Copyright (C) 2001-2010 Guan Xuetao
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  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 #include <mach/hardware.h>
  25
  26 struct pwm_device {
  27         struct list_head        node;
  28         struct platform_device *pdev;
  29
  30         const char      *label;
  31         struct clk      *clk;
  32         int             clk_enabled;
  33
  34         unsigned int    use_count;
  35         unsigned int    pwm_id;
  36 };
  37
  38 /*
  39  * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
  40  * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
  41  */
  42 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  43 {
  44         unsigned long long c;
  45         unsigned long period_cycles, prescale, pv, dc;
  46
  47         if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
  48                 return -EINVAL;
  49
  50         c = clk_get_rate(pwm->clk);
  51         c = c * period_ns;
  52         do_div(c, 1000000000);
  53         period_cycles = c;
  54
  55         if (period_cycles < 1)
  56                 period_cycles = 1;
  57         prescale = (period_cycles - 1) / 1024;
  58         pv = period_cycles / (prescale + 1) - 1;
  59
  60         if (prescale > 63)
  61                 return -EINVAL;
  62
  63         if (duty_ns == period_ns)
  64                 dc = OST_PWMDCCR_FDCYCLE;
  65         else
  66                 dc = (pv + 1) * duty_ns / period_ns;
  67
  68         /* NOTE: the clock to PWM has to be enabled first
  69          * before writing to the registers
  70          */
  71         clk_enable(pwm->clk);
  72         OST_PWMPWCR = prescale;
  73         OST_PWMDCCR = pv - dc;
  74         OST_PWMPCR  = pv;
  75         clk_disable(pwm->clk);
  76
  77         return 0;
  78 }
  79 EXPORT_SYMBOL(pwm_config);
  80
  81 int pwm_enable(struct pwm_device *pwm)
  82 {
  83         int rc = 0;
  84
  85         if (!pwm->clk_enabled) {
  86                 rc = clk_enable(pwm->clk);
  87                 if (!rc)
  88                         pwm->clk_enabled = 1;
  89         }
  90         return rc;
  91 }
  92 EXPORT_SYMBOL(pwm_enable);
  93
  94 void pwm_disable(struct pwm_device *pwm)
  95 {
  96         if (pwm->clk_enabled) {
  97                 clk_disable(pwm->clk);
  98                 pwm->clk_enabled = 0;
  99         }
 100 }
 101 EXPORT_SYMBOL(pwm_disable);
 102
 103 static DEFINE_MUTEX(pwm_lock);
 104 static LIST_HEAD(pwm_list);
 105
 106 struct pwm_device *pwm_request(int pwm_id, const char *label)
 107 {
 108         struct pwm_device *pwm;
 109         int found = 0;
 110
 111         mutex_lock(&pwm_lock);
 112
 113         list_for_each_entry(pwm, &pwm_list, node) {
 114                 if (pwm->pwm_id == pwm_id) {
 115                         found = 1;
 116                         break;
 117                 }
 118         }
 119
 120         if (found) {
 121                 if (pwm->use_count == 0) {
 122                         pwm->use_count++;
 123                         pwm->label = label;
 124                 } else
 125                         pwm = ERR_PTR(-EBUSY);
 126         } else
 127                 pwm = ERR_PTR(-ENOENT);
 128
 129         mutex_unlock(&pwm_lock);
 130         return pwm;
 131 }
 132 EXPORT_SYMBOL(pwm_request);
 133
 134 void pwm_free(struct pwm_device *pwm)
 135 {
 136         mutex_lock(&pwm_lock);
 137
 138         if (pwm->use_count) {
 139                 pwm->use_count--;
 140                 pwm->label = NULL;
 141         } else
 142                 pr_warning("PWM device already freed\n");
 143
 144         mutex_unlock(&pwm_lock);
 145 }
 146 EXPORT_SYMBOL(pwm_free);
 147
 148 static inline void __add_pwm(struct pwm_device *pwm)
 149 {
 150         mutex_lock(&pwm_lock);
 151         list_add_tail(&pwm->node, &pwm_list);
 152         mutex_unlock(&pwm_lock);
 153 }
 154
 155 static struct pwm_device *pwm_probe(struct platform_device *pdev,
 156                 unsigned int pwm_id, struct pwm_device *parent_pwm)
 157 {
 158         struct pwm_device *pwm;
 159         struct resource *r;
 160         int ret = 0;
 161
 162         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 163         if (pwm == NULL) {
 164                 dev_err(&pdev->dev, "failed to allocate memory\n");
 165                 return ERR_PTR(-ENOMEM);
 166         }
 167
 168         pwm->clk = clk_get(NULL, "OST_CLK");
 169         if (IS_ERR(pwm->clk)) {
 170                 ret = PTR_ERR(pwm->clk);
 171                 goto err_free;
 172         }
 173         pwm->clk_enabled = 0;
 174
 175         pwm->use_count = 0;
 176         pwm->pwm_id = pwm_id;
 177         pwm->pdev = pdev;
 178
 179         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 180         if (r == NULL) {
 181                 dev_err(&pdev->dev, "no memory resource defined\n");
 182                 ret = -ENODEV;
 183                 goto err_free_clk;
 184         }
 185
 186         r = request_mem_region(r->start, resource_size(r), pdev->name);
 187         if (r == NULL) {
 188                 dev_err(&pdev->dev, "failed to request memory resource\n");
 189                 ret = -EBUSY;
 190                 goto err_free_clk;
 191         }
 192
 193         __add_pwm(pwm);
 194         platform_set_drvdata(pdev, pwm);
 195         return pwm;
 196
 197 err_free_clk:
 198         clk_put(pwm->clk);
 199 err_free:
 200         kfree(pwm);
 201         return ERR_PTR(ret);
 202 }
 203
 204 static int __devinit puv3_pwm_probe(struct platform_device *pdev)
 205 {
 206         struct pwm_device *pwm = pwm_probe(pdev, pdev->id, NULL);
 207
 208         if (IS_ERR(pwm))
 209                 return PTR_ERR(pwm);
 210
 211         return 0;
 212 }
 213
 214 static int __devexit pwm_remove(struct platform_device *pdev)
 215 {
 216         struct pwm_device *pwm;
 217         struct resource *r;
 218
 219         pwm = platform_get_drvdata(pdev);
 220         if (pwm == NULL)
 221                 return -ENODEV;
 222
 223         mutex_lock(&pwm_lock);
 224         list_del(&pwm->node);
 225         mutex_unlock(&pwm_lock);
 226
 227         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 228         release_mem_region(r->start, resource_size(r));
 229
 230         clk_put(pwm->clk);
 231         kfree(pwm);
 232         return 0;
 233 }
 234
 235 static struct platform_driver puv3_pwm_driver = {
 236         .driver         = {
 237                 .name   = "PKUnity-v3-PWM",
 238         },
 239         .probe          = puv3_pwm_probe,
 240         .remove         = __devexit_p(pwm_remove),
 241 };
 242
 243 static int __init pwm_init(void)
 244 {
 245         int ret = 0;
 246
 247         ret = platform_driver_register(&puv3_pwm_driver);
 248         if (ret) {
 249                 printk(KERN_ERR "failed to register puv3_pwm_driver\n");
 250                 return ret;
 251         }
 252
 253         return ret;
 254 }
 255 arch_initcall(pwm_init);
 256
 257 static void __exit pwm_exit(void)
 258 {
 259         platform_driver_unregister(&puv3_pwm_driver);
 260 }
 261 module_exit(pwm_exit);
 262
 263 MODULE_LICENSE("GPL v2");