drivers/clocksource/sh_mtu2.c

   1 /*
   2  * SuperH Timer Support - MTU2
   3  *
   4  *  Copyright (C) 2009 Magnus Damm
   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 as published by
   8  * the Free Software Foundation; either version 2 of the License
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 #include <linux/init.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/ioport.h>
  25 #include <linux/delay.h>
  26 #include <linux/io.h>
  27 #include <linux/clk.h>
  28 #include <linux/irq.h>
  29 #include <linux/err.h>
  30 #include <linux/clockchips.h>
  31 #include <linux/sh_timer.h>
  32 #include <linux/slab.h>
  33 #include <linux/module.h>
  34
  35 struct sh_mtu2_priv {
  36         void __iomem *mapbase;
  37         struct clk *clk;
  38         struct irqaction irqaction;
  39         struct platform_device *pdev;
  40         unsigned long rate;
  41         unsigned long periodic;
  42         struct clock_event_device ced;
  43 };
  44
  45 static DEFINE_SPINLOCK(sh_mtu2_lock);
  46
  47 #define TSTR -1 /* shared register */
  48 #define TCR  0 /* channel register */
  49 #define TMDR 1 /* channel register */
  50 #define TIOR 2 /* channel register */
  51 #define TIER 3 /* channel register */
  52 #define TSR  4 /* channel register */
  53 #define TCNT 5 /* channel register */
  54 #define TGR  6 /* channel register */
  55
  56 static unsigned long mtu2_reg_offs[] = {
  57         [TCR] = 0,
  58         [TMDR] = 1,
  59         [TIOR] = 2,
  60         [TIER] = 4,
  61         [TSR] = 5,
  62         [TCNT] = 6,
  63         [TGR] = 8,
  64 };
  65
  66 static inline unsigned long sh_mtu2_read(struct sh_mtu2_priv *p, int reg_nr)
  67 {
  68         struct sh_timer_config *cfg = p->pdev->dev.platform_data;
  69         void __iomem *base = p->mapbase;
  70         unsigned long offs;
  71
  72         if (reg_nr == TSTR)
  73                 return ioread8(base + cfg->channel_offset);
  74
  75         offs = mtu2_reg_offs[reg_nr];
  76
  77         if ((reg_nr == TCNT) || (reg_nr == TGR))
  78                 return ioread16(base + offs);
  79         else
  80                 return ioread8(base + offs);
  81 }
  82
  83 static inline void sh_mtu2_write(struct sh_mtu2_priv *p, int reg_nr,
  84                                 unsigned long value)
  85 {
  86         struct sh_timer_config *cfg = p->pdev->dev.platform_data;
  87         void __iomem *base = p->mapbase;
  88         unsigned long offs;
  89
  90         if (reg_nr == TSTR) {
  91                 iowrite8(value, base + cfg->channel_offset);
  92                 return;
  93         }
  94
  95         offs = mtu2_reg_offs[reg_nr];
  96
  97         if ((reg_nr == TCNT) || (reg_nr == TGR))
  98                 iowrite16(value, base + offs);
  99         else
 100                 iowrite8(value, base + offs);
 101 }
 102
 103 static void sh_mtu2_start_stop_ch(struct sh_mtu2_priv *p, int start)
 104 {
 105         struct sh_timer_config *cfg = p->pdev->dev.platform_data;
 106         unsigned long flags, value;
 107
 108         /* start stop register shared by multiple timer channels */
 109         spin_lock_irqsave(&sh_mtu2_lock, flags);
 110         value = sh_mtu2_read(p, TSTR);
 111
 112         if (start)
 113                 value |= 1 << cfg->timer_bit;
 114         else
 115                 value &= ~(1 << cfg->timer_bit);
 116
 117         sh_mtu2_write(p, TSTR, value);
 118         spin_unlock_irqrestore(&sh_mtu2_lock, flags);
 119 }
 120
 121 static int sh_mtu2_enable(struct sh_mtu2_priv *p)
 122 {
 123         int ret;
 124
 125         /* enable clock */
 126         ret = clk_enable(p->clk);
 127         if (ret) {
 128                 dev_err(&p->pdev->dev, "cannot enable clock\n");
 129                 return ret;
 130         }
 131
 132         /* make sure channel is disabled */
 133         sh_mtu2_start_stop_ch(p, 0);
 134
 135         p->rate = clk_get_rate(p->clk) / 64;
 136         p->periodic = (p->rate + HZ/2) / HZ;
 137
 138         /* "Periodic Counter Operation" */
 139         sh_mtu2_write(p, TCR, 0x23); /* TGRA clear, divide clock by 64 */
 140         sh_mtu2_write(p, TIOR, 0);
 141         sh_mtu2_write(p, TGR, p->periodic);
 142         sh_mtu2_write(p, TCNT, 0);
 143         sh_mtu2_write(p, TMDR, 0);
 144         sh_mtu2_write(p, TIER, 0x01);
 145
 146         /* enable channel */
 147         sh_mtu2_start_stop_ch(p, 1);
 148
 149         return 0;
 150 }
 151
 152 static void sh_mtu2_disable(struct sh_mtu2_priv *p)
 153 {
 154         /* disable channel */
 155         sh_mtu2_start_stop_ch(p, 0);
 156
 157         /* stop clock */
 158         clk_disable(p->clk);
 159 }
 160
 161 static irqreturn_t sh_mtu2_interrupt(int irq, void *dev_id)
 162 {
 163         struct sh_mtu2_priv *p = dev_id;
 164
 165         /* acknowledge interrupt */
 166         sh_mtu2_read(p, TSR);
 167         sh_mtu2_write(p, TSR, 0xfe);
 168
 169         /* notify clockevent layer */
 170         p->ced.event_handler(&p->ced);
 171         return IRQ_HANDLED;
 172 }
 173
 174 static struct sh_mtu2_priv *ced_to_sh_mtu2(struct clock_event_device *ced)
 175 {
 176         return container_of(ced, struct sh_mtu2_priv, ced);
 177 }
 178
 179 static void sh_mtu2_clock_event_mode(enum clock_event_mode mode,
 180                                     struct clock_event_device *ced)
 181 {
 182         struct sh_mtu2_priv *p = ced_to_sh_mtu2(ced);
 183         int disabled = 0;
 184
 185         /* deal with old setting first */
 186         switch (ced->mode) {
 187         case CLOCK_EVT_MODE_PERIODIC:
 188                 sh_mtu2_disable(p);
 189                 disabled = 1;
 190                 break;
 191         default:
 192                 break;
 193         }
 194
 195         switch (mode) {
 196         case CLOCK_EVT_MODE_PERIODIC:
 197                 dev_info(&p->pdev->dev, "used for periodic clock events\n");
 198                 sh_mtu2_enable(p);
 199                 break;
 200         case CLOCK_EVT_MODE_UNUSED:
 201                 if (!disabled)
 202                         sh_mtu2_disable(p);
 203                 break;
 204         case CLOCK_EVT_MODE_SHUTDOWN:
 205         default:
 206                 break;
 207         }
 208 }
 209
 210 static void sh_mtu2_register_clockevent(struct sh_mtu2_priv *p,
 211                                        char *name, unsigned long rating)
 212 {
 213         struct clock_event_device *ced = &p->ced;
 214         int ret;
 215
 216         memset(ced, 0, sizeof(*ced));
 217
 218         ced->name = name;
 219         ced->features = CLOCK_EVT_FEAT_PERIODIC;
 220         ced->rating = rating;
 221         ced->cpumask = cpumask_of(0);
 222         ced->set_mode = sh_mtu2_clock_event_mode;
 223
 224         dev_info(&p->pdev->dev, "used for clock events\n");
 225         clockevents_register_device(ced);
 226
 227         ret = setup_irq(p->irqaction.irq, &p->irqaction);
 228         if (ret) {
 229                 dev_err(&p->pdev->dev, "failed to request irq %d\n",
 230                         p->irqaction.irq);
 231                 return;
 232         }
 233 }
 234
 235 static int sh_mtu2_register(struct sh_mtu2_priv *p, char *name,
 236                             unsigned long clockevent_rating)
 237 {
 238         if (clockevent_rating)
 239                 sh_mtu2_register_clockevent(p, name, clockevent_rating);
 240
 241         return 0;
 242 }
 243
 244 static int sh_mtu2_setup(struct sh_mtu2_priv *p, struct platform_device *pdev)
 245 {
 246         struct sh_timer_config *cfg = pdev->dev.platform_data;
 247         struct resource *res;
 248         int irq, ret;
 249         ret = -ENXIO;
 250
 251         memset(p, 0, sizeof(*p));
 252         p->pdev = pdev;
 253
 254         if (!cfg) {
 255                 dev_err(&p->pdev->dev, "missing platform data\n");
 256                 goto err0;
 257         }
 258
 259         platform_set_drvdata(pdev, p);
 260
 261         res = platform_get_resource(p->pdev, IORESOURCE_MEM, 0);
 262         if (!res) {
 263                 dev_err(&p->pdev->dev, "failed to get I/O memory\n");
 264                 goto err0;
 265         }
 266
 267         irq = platform_get_irq(p->pdev, 0);
 268         if (irq < 0) {
 269                 dev_err(&p->pdev->dev, "failed to get irq\n");
 270                 goto err0;
 271         }
 272
 273         /* map memory, let mapbase point to our channel */
 274         p->mapbase = ioremap_nocache(res->start, resource_size(res));
 275         if (p->mapbase == NULL) {
 276                 dev_err(&p->pdev->dev, "failed to remap I/O memory\n");
 277                 goto err0;
 278         }
 279
 280         /* setup data for setup_irq() (too early for request_irq()) */
 281         p->irqaction.name = dev_name(&p->pdev->dev);
 282         p->irqaction.handler = sh_mtu2_interrupt;
 283         p->irqaction.dev_id = p;
 284         p->irqaction.irq = irq;
 285         p->irqaction.flags = IRQF_DISABLED | IRQF_TIMER | \
 286                              IRQF_IRQPOLL  | IRQF_NOBALANCING;
 287
 288         /* get hold of clock */
 289         p->clk = clk_get(&p->pdev->dev, "mtu2_fck");
 290         if (IS_ERR(p->clk)) {
 291                 dev_err(&p->pdev->dev, "cannot get clock\n");
 292                 ret = PTR_ERR(p->clk);
 293                 goto err1;
 294         }
 295
 296         return sh_mtu2_register(p, (char *)dev_name(&p->pdev->dev),
 297                                 cfg->clockevent_rating);
 298  err1:
 299         iounmap(p->mapbase);
 300  err0:
 301         return ret;
 302 }
 303
 304 static int __devinit sh_mtu2_probe(struct platform_device *pdev)
 305 {
 306         struct sh_mtu2_priv *p = platform_get_drvdata(pdev);
 307         int ret;
 308
 309         if (p) {
 310                 dev_info(&pdev->dev, "kept as earlytimer\n");
 311                 return 0;
 312         }
 313
 314         p = kmalloc(sizeof(*p), GFP_KERNEL);
 315         if (p == NULL) {
 316                 dev_err(&pdev->dev, "failed to allocate driver data\n");
 317                 return -ENOMEM;
 318         }
 319
 320         ret = sh_mtu2_setup(p, pdev);
 321         if (ret) {
 322                 kfree(p);
 323                 platform_set_drvdata(pdev, NULL);
 324         }
 325         return ret;
 326 }
 327
 328 static int __devexit sh_mtu2_remove(struct platform_device *pdev)
 329 {
 330         return -EBUSY; /* cannot unregister clockevent */
 331 }
 332
 333 static struct platform_driver sh_mtu2_device_driver = {
 334         .probe          = sh_mtu2_probe,
 335         .remove         = __devexit_p(sh_mtu2_remove),
 336         .driver         = {
 337                 .name   = "sh_mtu2",
 338         }
 339 };
 340
 341 static int __init sh_mtu2_init(void)
 342 {
 343         return platform_driver_register(&sh_mtu2_device_driver);
 344 }
 345
 346 static void __exit sh_mtu2_exit(void)
 347 {
 348         platform_driver_unregister(&sh_mtu2_device_driver);
 349 }
 350
 351 early_platform_init("earlytimer", &sh_mtu2_device_driver);
 352 module_init(sh_mtu2_init);
 353 module_exit(sh_mtu2_exit);
 354
 355 MODULE_AUTHOR("Magnus Damm");
 356 MODULE_DESCRIPTION("SuperH MTU2 Timer Driver");
 357 MODULE_LICENSE("GPL v2");