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
  33 struct sh_mtu2_priv {
  34         void __iomem *mapbase;
  35         struct clk *clk;
  36         struct irqaction irqaction;
  37         struct platform_device *pdev;
  38         unsigned long rate;
  39         unsigned long periodic;
  40         struct clock_event_device ced;
  41 };
  42
  43 static DEFINE_SPINLOCK(sh_mtu2_lock);
  44
  45 #define TSTR -1 /* shared register */
  46 #define TCR  0 /* channel register */
  47 #define TMDR 1 /* channel register */
  48 #define TIOR 2 /* channel register */
  49 #define TIER 3 /* channel register */
  50 #define TSR  4 /* channel register */
  51 #define TCNT 5 /* channel register */
  52 #define TGR  6 /* channel register */
  53
  54 static unsigned long mtu2_reg_offs[] = {
  55         [TCR] = 0,
  56         [TMDR] = 1,
  57         [TIOR] = 2,
  58         [TIER] = 4,
  59         [TSR] = 5,
  60         [TCNT] = 6,
  61         [TGR] = 8,
  62 };
  63
  64 static inline unsigned long sh_mtu2_read(struct sh_mtu2_priv *p, int reg_nr)
  65 {
  66         struct sh_timer_config *cfg = p->pdev->dev.platform_data;
  67         void __iomem *base = p->mapbase;
  68         unsigned long offs;
  69
  70         if (reg_nr == TSTR)
  71                 return ioread8(base + cfg->channel_offset);
  72
  73         offs = mtu2_reg_offs[reg_nr];
  74
  75         if ((reg_nr == TCNT) || (reg_nr == TGR))
  76                 return ioread16(base + offs);
  77         else
  78                 return ioread8(base + offs);
  79 }
  80
  81 static inline void sh_mtu2_write(struct sh_mtu2_priv *p, int reg_nr,
  82                                 unsigned long value)
  83 {
  84         struct sh_timer_config *cfg = p->pdev->dev.platform_data;
  85         void __iomem *base = p->mapbase;
  86         unsigned long offs;
  87
  88         if (reg_nr == TSTR) {
  89                 iowrite8(value, base + cfg->channel_offset);
  90                 return;
  91         }
  92
  93         offs = mtu2_reg_offs[reg_nr];
  94
  95         if ((reg_nr == TCNT) || (reg_nr == TGR))
  96                 iowrite16(value, base + offs);
  97         else
  98                 iowrite8(value, base + offs);
  99 }
 100
 101 static void sh_mtu2_start_stop_ch(struct sh_mtu2_priv *p, int start)
 102 {
 103         struct sh_timer_config *cfg = p->pdev->dev.platform_data;
 104         unsigned long flags, value;
 105
 106         /* start stop register shared by multiple timer channels */
 107         spin_lock_irqsave(&sh_mtu2_lock, flags);
 108         value = sh_mtu2_read(p, TSTR);
 109
 110         if (start)
 111                 value |= 1 << cfg->timer_bit;
 112         else
 113                 value &= ~(1 << cfg->timer_bit);
 114
 115         sh_mtu2_write(p, TSTR, value);
 116         spin_unlock_irqrestore(&sh_mtu2_lock, flags);
 117 }
 118
 119 static int sh_mtu2_enable(struct sh_mtu2_priv *p)
 120 {
 121         struct sh_timer_config *cfg = p->pdev->dev.platform_data;
 122         int ret;
 123
 124         /* enable clock */
 125         ret = clk_enable(p->clk);
 126         if (ret) {
 127                 pr_err("sh_mtu2: cannot enable clock \"%s\"\n", cfg->clk);
 128                 return ret;
 129         }
 130
 131         /* make sure channel is disabled */
 132         sh_mtu2_start_stop_ch(p, 0);
 133
 134         p->rate = clk_get_rate(p->clk) / 64;
 135         p->periodic = (p->rate + HZ/2) / HZ;
 136
 137         /* "Periodic Counter Operation" */
 138         sh_mtu2_write(p, TCR, 0x23); /* TGRA clear, divide clock by 64 */
 139         sh_mtu2_write(p, TIOR, 0);
 140         sh_mtu2_write(p, TGR, p->periodic);
 141         sh_mtu2_write(p, TCNT, 0);
 142         sh_mtu2_write(p, TMDR, 0);
 143         sh_mtu2_write(p, TIER, 0x01);
 144
 145         /* enable channel */
 146         sh_mtu2_start_stop_ch(p, 1);
 147
 148         return 0;
 149 }
 150
 151 static void sh_mtu2_disable(struct sh_mtu2_priv *p)
 152 {
 153         /* disable channel */
 154         sh_mtu2_start_stop_ch(p, 0);
 155
 156         /* stop clock */
 157         clk_disable(p->clk);
 158 }
 159
 160 static irqreturn_t sh_mtu2_interrupt(int irq, void *dev_id)
 161 {
 162         struct sh_mtu2_priv *p = dev_id;
 163
 164         /* acknowledge interrupt */
 165         sh_mtu2_read(p, TSR);
 166         sh_mtu2_write(p, TSR, 0xfe);
 167
 168         /* notify clockevent layer */
 169         p->ced.event_handler(&p->ced);
 170         return IRQ_HANDLED;
 171 }
 172
 173 static struct sh_mtu2_priv *ced_to_sh_mtu2(struct clock_event_device *ced)
 174 {
 175         return container_of(ced, struct sh_mtu2_priv, ced);
 176 }
 177
 178 static void sh_mtu2_clock_event_mode(enum clock_event_mode mode,
 179                                     struct clock_event_device *ced)
 180 {
 181         struct sh_mtu2_priv *p = ced_to_sh_mtu2(ced);
 182         int disabled = 0;
 183
 184         /* deal with old setting first */
 185         switch (ced->mode) {
 186         case CLOCK_EVT_MODE_PERIODIC:
 187                 sh_mtu2_disable(p);
 188                 disabled = 1;
 189                 break;
 190         default:
 191                 break;
 192         }
 193
 194         switch (mode) {
 195         case CLOCK_EVT_MODE_PERIODIC:
 196                 pr_info("sh_mtu2: %s used for periodic clock events\n",
 197                         ced->name);
 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         ret = setup_irq(p->irqaction.irq, &p->irqaction);
 225         if (ret) {
 226                 pr_err("sh_mtu2: failed to request irq %d\n",
 227                        p->irqaction.irq);
 228                 return;
 229         }
 230
 231         pr_info("sh_mtu2: %s used for clock events\n", ced->name);
 232         clockevents_register_device(ced);
 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                 pr_err("sh_mtu2: 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 = cfg->name;
 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 | IRQF_IRQPOLL;
 286
 287         /* get hold of clock */
 288         p->clk = clk_get(&p->pdev->dev, cfg->clk);
 289         if (IS_ERR(p->clk)) {
 290                 pr_err("sh_mtu2: cannot get clock \"%s\"\n", cfg->clk);
 291                 ret = PTR_ERR(p->clk);
 292                 goto err1;
 293         }
 294
 295         return sh_mtu2_register(p, cfg->name, cfg->clockevent_rating);
 296  err1:
 297         iounmap(p->mapbase);
 298  err0:
 299         return ret;
 300 }
 301
 302 static int __devinit sh_mtu2_probe(struct platform_device *pdev)
 303 {
 304         struct sh_mtu2_priv *p = platform_get_drvdata(pdev);
 305         struct sh_timer_config *cfg = pdev->dev.platform_data;
 306         int ret;
 307
 308         if (p) {
 309                 pr_info("sh_mtu2: %s kept as earlytimer\n", cfg->name);
 310                 return 0;
 311         }
 312
 313         p = kmalloc(sizeof(*p), GFP_KERNEL);
 314         if (p == NULL) {
 315                 dev_err(&pdev->dev, "failed to allocate driver data\n");
 316                 return -ENOMEM;
 317         }
 318
 319         ret = sh_mtu2_setup(p, pdev);
 320         if (ret) {
 321                 kfree(p);
 322                 platform_set_drvdata(pdev, NULL);
 323         }
 324         return ret;
 325 }
 326
 327 static int __devexit sh_mtu2_remove(struct platform_device *pdev)
 328 {
 329         return -EBUSY; /* cannot unregister clockevent */
 330 }
 331
 332 static struct platform_driver sh_mtu2_device_driver = {
 333         .probe          = sh_mtu2_probe,
 334         .remove         = __devexit_p(sh_mtu2_remove),
 335         .driver         = {
 336                 .name   = "sh_mtu2",
 337         }
 338 };
 339
 340 static int __init sh_mtu2_init(void)
 341 {
 342         return platform_driver_register(&sh_mtu2_device_driver);
 343 }
 344
 345 static void __exit sh_mtu2_exit(void)
 346 {
 347         platform_driver_unregister(&sh_mtu2_device_driver);
 348 }
 349
 350 early_platform_init("earlytimer", &sh_mtu2_device_driver);
 351 module_init(sh_mtu2_init);
 352 module_exit(sh_mtu2_exit);
 353
 354 MODULE_AUTHOR("Magnus Damm");
 355 MODULE_DESCRIPTION("SuperH MTU2 Timer Driver");
 356 MODULE_LICENSE("GPL v2");