arch/powerpc/platforms/52xx/mpc52xx_gpt.c

   1 /*
   2  * MPC5200 General Purpose Timer device driver
   3  *
   4  * Copyright (c) 2009 Secret Lab Technologies Ltd.
   5  * Copyright (c) 2008 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
   6  *
   7  * This program is free software; you can redistribute  it and/or modify it
   8  * under  the terms of  the GNU General  Public License as published by the
   9  * Free Software Foundation;  either version 2 of the  License, or (at your
  10  * option) any later version.
  11  *
  12  * This file is a driver for the the General Purpose Timer (gpt) devices
  13  * found on the MPC5200 SoC.  Each timer has an IO pin which can be used
  14  * for GPIO or can be used to raise interrupts.  The timer function can
  15  * be used independently from the IO pin, or it can be used to control
  16  * output signals or measure input signals.
  17  *
  18  * This driver supports the GPIO and IRQ controller functions of the GPT
  19  * device.  Timer functions are not yet supported.
  20  *
  21  * The timer gpt0 can be used as watchdog (wdt).  If the wdt mode is used,
  22  * this prevents the use of any gpt0 gpt function (i.e. they will fail with
  23  * -EBUSY).  Thus, the safety wdt function always has precedence over the gpt
  24  * function.  If the kernel has been compiled with CONFIG_WATCHDOG_NOWAYOUT,
  25  * this means that gpt0 is locked in wdt mode until the next reboot - this
  26  * may be a requirement in safety applications.
  27  *
  28  * To use the GPIO function, the following two properties must be added
  29  * to the device tree node for the gpt device (typically in the .dts file
  30  * for the board):
  31  *      gpio-controller;
  32  *      #gpio-cells = < 2 >;
  33  * This driver will register the GPIO pin if it finds the gpio-controller
  34  * property in the device tree.
  35  *
  36  * To use the IRQ controller function, the following two properties must
  37  * be added to the device tree node for the gpt device:
  38  *      interrupt-controller;
  39  *      #interrupt-cells = < 1 >;
  40  * The IRQ controller binding only uses one cell to specify the interrupt,
  41  * and the IRQ flags are encoded in the cell.  A cell is not used to encode
  42  * the IRQ number because the GPT only has a single IRQ source.  For flags,
  43  * a value of '1' means rising edge sensitive and '2' means falling edge.
  44  *
  45  * The GPIO and the IRQ controller functions can be used at the same time,
  46  * but in this use case the IO line will only work as an input.  Trying to
  47  * use it as a GPIO output will not work.
  48  *
  49  * When using the GPIO line as an output, it can either be driven as normal
  50  * IO, or it can be an Open Collector (OC) output.  At the moment it is the
  51  * responsibility of either the bootloader or the platform setup code to set
  52  * the output mode.  This driver does not change the output mode setting.
  53  */
  54
  55 #include <linux/device.h>
  56 #include <linux/irq.h>
  57 #include <linux/interrupt.h>
  58 #include <linux/io.h>
  59 #include <linux/list.h>
  60 #include <linux/mutex.h>
  61 #include <linux/of.h>
  62 #include <linux/of_platform.h>
  63 #include <linux/of_gpio.h>
  64 #include <linux/kernel.h>
  65 #include <linux/slab.h>
  66 #include <linux/fs.h>
  67 #include <linux/watchdog.h>
  68 #include <linux/miscdevice.h>
  69 #include <linux/uaccess.h>
  70 #include <linux/module.h>
  71 #include <asm/div64.h>
  72 #include <asm/mpc52xx.h>
  73
  74 MODULE_DESCRIPTION("Freescale MPC52xx gpt driver");
  75 MODULE_AUTHOR("Sascha Hauer, Grant Likely, Albrecht Dreß");
  76 MODULE_LICENSE("GPL");
  77
  78 /**
  79  * struct mpc52xx_gpt - Private data structure for MPC52xx GPT driver
  80  * @dev: pointer to device structure
  81  * @regs: virtual address of GPT registers
  82  * @lock: spinlock to coordinate between different functions.
  83  * @gc: gpio_chip instance structure; used when GPIO is enabled
  84  * @irqhost: Pointer to irq_domain instance; used when IRQ mode is supported
  85  * @wdt_mode: only relevant for gpt0: bit 0 (MPC52xx_GPT_CAN_WDT) indicates
  86  *   if the gpt may be used as wdt, bit 1 (MPC52xx_GPT_IS_WDT) indicates
  87  *   if the timer is actively used as wdt which blocks gpt functions
  88  */
  89 struct mpc52xx_gpt_priv {
  90         struct list_head list;          /* List of all GPT devices */
  91         struct device *dev;
  92         struct mpc52xx_gpt __iomem *regs;
  93         raw_spinlock_t lock;
  94         struct irq_domain *irqhost;
  95         u32 ipb_freq;
  96         u8 wdt_mode;
  97
  98 #if defined(CONFIG_GPIOLIB)
  99         struct gpio_chip gc;
 100 #endif
 101 };
 102
 103 LIST_HEAD(mpc52xx_gpt_list);
 104 DEFINE_MUTEX(mpc52xx_gpt_list_mutex);
 105
 106 #define MPC52xx_GPT_MODE_MS_MASK        (0x07)
 107 #define MPC52xx_GPT_MODE_MS_IC          (0x01)
 108 #define MPC52xx_GPT_MODE_MS_OC          (0x02)
 109 #define MPC52xx_GPT_MODE_MS_PWM         (0x03)
 110 #define MPC52xx_GPT_MODE_MS_GPIO        (0x04)
 111
 112 #define MPC52xx_GPT_MODE_GPIO_MASK      (0x30)
 113 #define MPC52xx_GPT_MODE_GPIO_OUT_LOW   (0x20)
 114 #define MPC52xx_GPT_MODE_GPIO_OUT_HIGH  (0x30)
 115
 116 #define MPC52xx_GPT_MODE_COUNTER_ENABLE (0x1000)
 117 #define MPC52xx_GPT_MODE_CONTINUOUS     (0x0400)
 118 #define MPC52xx_GPT_MODE_OPEN_DRAIN     (0x0200)
 119 #define MPC52xx_GPT_MODE_IRQ_EN         (0x0100)
 120 #define MPC52xx_GPT_MODE_WDT_EN         (0x8000)
 121
 122 #define MPC52xx_GPT_MODE_ICT_MASK       (0x030000)
 123 #define MPC52xx_GPT_MODE_ICT_RISING     (0x010000)
 124 #define MPC52xx_GPT_MODE_ICT_FALLING    (0x020000)
 125 #define MPC52xx_GPT_MODE_ICT_TOGGLE     (0x030000)
 126
 127 #define MPC52xx_GPT_MODE_WDT_PING       (0xa5)
 128
 129 #define MPC52xx_GPT_STATUS_IRQMASK      (0x000f)
 130
 131 #define MPC52xx_GPT_CAN_WDT             (1 << 0)
 132 #define MPC52xx_GPT_IS_WDT              (1 << 1)
 133
 134
 135 /* ---------------------------------------------------------------------
 136  * Cascaded interrupt controller hooks
 137  */
 138
 139 static void mpc52xx_gpt_irq_unmask(struct irq_data *d)
 140 {
 141         struct mpc52xx_gpt_priv *gpt = irq_data_get_irq_chip_data(d);
 142         unsigned long flags;
 143
 144         raw_spin_lock_irqsave(&gpt->lock, flags);
 145         setbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_IRQ_EN);
 146         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 147 }
 148
 149 static void mpc52xx_gpt_irq_mask(struct irq_data *d)
 150 {
 151         struct mpc52xx_gpt_priv *gpt = irq_data_get_irq_chip_data(d);
 152         unsigned long flags;
 153
 154         raw_spin_lock_irqsave(&gpt->lock, flags);
 155         clrbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_IRQ_EN);
 156         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 157 }
 158
 159 static void mpc52xx_gpt_irq_ack(struct irq_data *d)
 160 {
 161         struct mpc52xx_gpt_priv *gpt = irq_data_get_irq_chip_data(d);
 162
 163         out_be32(&gpt->regs->status, MPC52xx_GPT_STATUS_IRQMASK);
 164 }
 165
 166 static int mpc52xx_gpt_irq_set_type(struct irq_data *d, unsigned int flow_type)
 167 {
 168         struct mpc52xx_gpt_priv *gpt = irq_data_get_irq_chip_data(d);
 169         unsigned long flags;
 170         u32 reg;
 171
 172         dev_dbg(gpt->dev, "%s: virq=%i type=%x\n", __func__, d->irq, flow_type);
 173
 174         raw_spin_lock_irqsave(&gpt->lock, flags);
 175         reg = in_be32(&gpt->regs->mode) & ~MPC52xx_GPT_MODE_ICT_MASK;
 176         if (flow_type & IRQF_TRIGGER_RISING)
 177                 reg |= MPC52xx_GPT_MODE_ICT_RISING;
 178         if (flow_type & IRQF_TRIGGER_FALLING)
 179                 reg |= MPC52xx_GPT_MODE_ICT_FALLING;
 180         out_be32(&gpt->regs->mode, reg);
 181         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 182
 183         return 0;
 184 }
 185
 186 static struct irq_chip mpc52xx_gpt_irq_chip = {
 187         .name = "MPC52xx GPT",
 188         .irq_unmask = mpc52xx_gpt_irq_unmask,
 189         .irq_mask = mpc52xx_gpt_irq_mask,
 190         .irq_ack = mpc52xx_gpt_irq_ack,
 191         .irq_set_type = mpc52xx_gpt_irq_set_type,
 192 };
 193
 194 static void mpc52xx_gpt_irq_cascade(struct irq_desc *desc)
 195 {
 196         struct mpc52xx_gpt_priv *gpt = irq_desc_get_handler_data(desc);
 197         int sub_virq;
 198         u32 status;
 199
 200         status = in_be32(&gpt->regs->status) & MPC52xx_GPT_STATUS_IRQMASK;
 201         if (status) {
 202                 sub_virq = irq_linear_revmap(gpt->irqhost, 0);
 203                 generic_handle_irq(sub_virq);
 204         }
 205 }
 206
 207 static int mpc52xx_gpt_irq_map(struct irq_domain *h, unsigned int virq,
 208                                irq_hw_number_t hw)
 209 {
 210         struct mpc52xx_gpt_priv *gpt = h->host_data;
 211
 212         dev_dbg(gpt->dev, "%s: h=%p, virq=%i\n", __func__, h, virq);
 213         irq_set_chip_data(virq, gpt);
 214         irq_set_chip_and_handler(virq, &mpc52xx_gpt_irq_chip, handle_edge_irq);
 215
 216         return 0;
 217 }
 218
 219 static int mpc52xx_gpt_irq_xlate(struct irq_domain *h, struct device_node *ct,
 220                                  const u32 *intspec, unsigned int intsize,
 221                                  irq_hw_number_t *out_hwirq,
 222                                  unsigned int *out_flags)
 223 {
 224         struct mpc52xx_gpt_priv *gpt = h->host_data;
 225
 226         dev_dbg(gpt->dev, "%s: flags=%i\n", __func__, intspec[0]);
 227
 228         if ((intsize < 1) || (intspec[0] > 3)) {
 229                 dev_err(gpt->dev, "bad irq specifier in %pOF\n", ct);
 230                 return -EINVAL;
 231         }
 232
 233         *out_hwirq = 0; /* The GPT only has 1 IRQ line */
 234         *out_flags = intspec[0];
 235
 236         return 0;
 237 }
 238
 239 static const struct irq_domain_ops mpc52xx_gpt_irq_ops = {
 240         .map = mpc52xx_gpt_irq_map,
 241         .xlate = mpc52xx_gpt_irq_xlate,
 242 };
 243
 244 static void
 245 mpc52xx_gpt_irq_setup(struct mpc52xx_gpt_priv *gpt, struct device_node *node)
 246 {
 247         int cascade_virq;
 248         unsigned long flags;
 249         u32 mode;
 250
 251         cascade_virq = irq_of_parse_and_map(node, 0);
 252         if (!cascade_virq)
 253                 return;
 254
 255         gpt->irqhost = irq_domain_add_linear(node, 1, &mpc52xx_gpt_irq_ops, gpt);
 256         if (!gpt->irqhost) {
 257                 dev_err(gpt->dev, "irq_domain_add_linear() failed\n");
 258                 return;
 259         }
 260
 261         irq_set_handler_data(cascade_virq, gpt);
 262         irq_set_chained_handler(cascade_virq, mpc52xx_gpt_irq_cascade);
 263
 264         /* If the GPT is currently disabled, then change it to be in Input
 265          * Capture mode.  If the mode is non-zero, then the pin could be
 266          * already in use for something. */
 267         raw_spin_lock_irqsave(&gpt->lock, flags);
 268         mode = in_be32(&gpt->regs->mode);
 269         if ((mode & MPC52xx_GPT_MODE_MS_MASK) == 0)
 270                 out_be32(&gpt->regs->mode, mode | MPC52xx_GPT_MODE_MS_IC);
 271         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 272
 273         dev_dbg(gpt->dev, "%s() complete. virq=%i\n", __func__, cascade_virq);
 274 }
 275
 276
 277 /* ---------------------------------------------------------------------
 278  * GPIOLIB hooks
 279  */
 280 #if defined(CONFIG_GPIOLIB)
 281 static int mpc52xx_gpt_gpio_get(struct gpio_chip *gc, unsigned int gpio)
 282 {
 283         struct mpc52xx_gpt_priv *gpt = gpiochip_get_data(gc);
 284
 285         return (in_be32(&gpt->regs->status) >> 8) & 1;
 286 }
 287
 288 static void
 289 mpc52xx_gpt_gpio_set(struct gpio_chip *gc, unsigned int gpio, int v)
 290 {
 291         struct mpc52xx_gpt_priv *gpt = gpiochip_get_data(gc);
 292         unsigned long flags;
 293         u32 r;
 294
 295         dev_dbg(gpt->dev, "%s: gpio:%d v:%d\n", __func__, gpio, v);
 296         r = v ? MPC52xx_GPT_MODE_GPIO_OUT_HIGH : MPC52xx_GPT_MODE_GPIO_OUT_LOW;
 297
 298         raw_spin_lock_irqsave(&gpt->lock, flags);
 299         clrsetbits_be32(&gpt->regs->mode, MPC52xx_GPT_MODE_GPIO_MASK, r);
 300         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 301 }
 302
 303 static int mpc52xx_gpt_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
 304 {
 305         struct mpc52xx_gpt_priv *gpt = gpiochip_get_data(gc);
 306         unsigned long flags;
 307
 308         dev_dbg(gpt->dev, "%s: gpio:%d\n", __func__, gpio);
 309
 310         raw_spin_lock_irqsave(&gpt->lock, flags);
 311         clrbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_GPIO_MASK);
 312         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 313
 314         return 0;
 315 }
 316
 317 static int
 318 mpc52xx_gpt_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
 319 {
 320         mpc52xx_gpt_gpio_set(gc, gpio, val);
 321         return 0;
 322 }
 323
 324 static void
 325 mpc52xx_gpt_gpio_setup(struct mpc52xx_gpt_priv *gpt, struct device_node *node)
 326 {
 327         int rc;
 328
 329         /* Only setup GPIO if the device tree claims the GPT is
 330          * a GPIO controller */
 331         if (!of_find_property(node, "gpio-controller", NULL))
 332                 return;
 333
 334         gpt->gc.label = kasprintf(GFP_KERNEL, "%pOF", node);
 335         if (!gpt->gc.label) {
 336                 dev_err(gpt->dev, "out of memory\n");
 337                 return;
 338         }
 339
 340         gpt->gc.ngpio = 1;
 341         gpt->gc.direction_input  = mpc52xx_gpt_gpio_dir_in;
 342         gpt->gc.direction_output = mpc52xx_gpt_gpio_dir_out;
 343         gpt->gc.get = mpc52xx_gpt_gpio_get;
 344         gpt->gc.set = mpc52xx_gpt_gpio_set;
 345         gpt->gc.base = -1;
 346         gpt->gc.of_node = node;
 347
 348         /* Setup external pin in GPIO mode */
 349         clrsetbits_be32(&gpt->regs->mode, MPC52xx_GPT_MODE_MS_MASK,
 350                         MPC52xx_GPT_MODE_MS_GPIO);
 351
 352         rc = gpiochip_add_data(&gpt->gc, gpt);
 353         if (rc)
 354                 dev_err(gpt->dev, "gpiochip_add_data() failed; rc=%i\n", rc);
 355
 356         dev_dbg(gpt->dev, "%s() complete.\n", __func__);
 357 }
 358 #else /* defined(CONFIG_GPIOLIB) */
 359 static void
 360 mpc52xx_gpt_gpio_setup(struct mpc52xx_gpt_priv *p, struct device_node *np) { }
 361 #endif /* defined(CONFIG_GPIOLIB) */
 362
 363 /***********************************************************************
 364  * Timer API
 365  */
 366
 367 /**
 368  * mpc52xx_gpt_from_irq - Return the GPT device associated with an IRQ number
 369  * @irq: irq of timer.
 370  */
 371 struct mpc52xx_gpt_priv *mpc52xx_gpt_from_irq(int irq)
 372 {
 373         struct mpc52xx_gpt_priv *gpt;
 374         struct list_head *pos;
 375
 376         /* Iterate over the list of timers looking for a matching device */
 377         mutex_lock(&mpc52xx_gpt_list_mutex);
 378         list_for_each(pos, &mpc52xx_gpt_list) {
 379                 gpt = container_of(pos, struct mpc52xx_gpt_priv, list);
 380                 if (gpt->irqhost && irq == irq_linear_revmap(gpt->irqhost, 0)) {
 381                         mutex_unlock(&mpc52xx_gpt_list_mutex);
 382                         return gpt;
 383                 }
 384         }
 385         mutex_unlock(&mpc52xx_gpt_list_mutex);
 386
 387         return NULL;
 388 }
 389 EXPORT_SYMBOL(mpc52xx_gpt_from_irq);
 390
 391 static int mpc52xx_gpt_do_start(struct mpc52xx_gpt_priv *gpt, u64 period,
 392                                 int continuous, int as_wdt)
 393 {
 394         u32 clear, set;
 395         u64 clocks;
 396         u32 prescale;
 397         unsigned long flags;
 398
 399         clear = MPC52xx_GPT_MODE_MS_MASK | MPC52xx_GPT_MODE_CONTINUOUS;
 400         set = MPC52xx_GPT_MODE_MS_GPIO | MPC52xx_GPT_MODE_COUNTER_ENABLE;
 401         if (as_wdt) {
 402                 clear |= MPC52xx_GPT_MODE_IRQ_EN;
 403                 set |= MPC52xx_GPT_MODE_WDT_EN;
 404         } else if (continuous)
 405                 set |= MPC52xx_GPT_MODE_CONTINUOUS;
 406
 407         /* Determine the number of clocks in the requested period.  64 bit
 408          * arithmatic is done here to preserve the precision until the value
 409          * is scaled back down into the u32 range.  Period is in 'ns', bus
 410          * frequency is in Hz. */
 411         clocks = period * (u64)gpt->ipb_freq;
 412         do_div(clocks, 1000000000); /* Scale it down to ns range */
 413
 414         /* This device cannot handle a clock count greater than 32 bits */
 415         if (clocks > 0xffffffff)
 416                 return -EINVAL;
 417
 418         /* Calculate the prescaler and count values from the clocks value.
 419          * 'clocks' is the number of clock ticks in the period.  The timer
 420          * has 16 bit precision and a 16 bit prescaler.  Prescaler is
 421          * calculated by integer dividing the clocks by 0x10000 (shifting
 422          * down 16 bits) to obtain the smallest possible divisor for clocks
 423          * to get a 16 bit count value.
 424          *
 425          * Note: the prescale register is '1' based, not '0' based.  ie. a
 426          * value of '1' means divide the clock by one.  0xffff divides the
 427          * clock by 0xffff.  '0x0000' does not divide by zero, but wraps
 428          * around and divides by 0x10000.  That is why prescale must be
 429          * a u32 variable, not a u16, for this calculation. */
 430         prescale = (clocks >> 16) + 1;
 431         do_div(clocks, prescale);
 432         if (clocks > 0xffff) {
 433                 pr_err("calculation error; prescale:%x clocks:%llx\n",
 434                        prescale, clocks);
 435                 return -EINVAL;
 436         }
 437
 438         /* Set and enable the timer, reject an attempt to use a wdt as gpt */
 439         raw_spin_lock_irqsave(&gpt->lock, flags);
 440         if (as_wdt)
 441                 gpt->wdt_mode |= MPC52xx_GPT_IS_WDT;
 442         else if ((gpt->wdt_mode & MPC52xx_GPT_IS_WDT) != 0) {
 443                 raw_spin_unlock_irqrestore(&gpt->lock, flags);
 444                 return -EBUSY;
 445         }
 446         out_be32(&gpt->regs->count, prescale << 16 | clocks);
 447         clrsetbits_be32(&gpt->regs->mode, clear, set);
 448         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 449
 450         return 0;
 451 }
 452
 453 /**
 454  * mpc52xx_gpt_start_timer - Set and enable the GPT timer
 455  * @gpt: Pointer to gpt private data structure
 456  * @period: period of timer in ns; max. ~130s @ 33MHz IPB clock
 457  * @continuous: set to 1 to make timer continuous free running
 458  *
 459  * An interrupt will be generated every time the timer fires
 460  */
 461 int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, u64 period,
 462                             int continuous)
 463 {
 464         return mpc52xx_gpt_do_start(gpt, period, continuous, 0);
 465 }
 466 EXPORT_SYMBOL(mpc52xx_gpt_start_timer);
 467
 468 /**
 469  * mpc52xx_gpt_stop_timer - Stop a gpt
 470  * @gpt: Pointer to gpt private data structure
 471  *
 472  * Returns an error if attempting to stop a wdt
 473  */
 474 int mpc52xx_gpt_stop_timer(struct mpc52xx_gpt_priv *gpt)
 475 {
 476         unsigned long flags;
 477
 478         /* reject the operation if the timer is used as watchdog (gpt 0 only) */
 479         raw_spin_lock_irqsave(&gpt->lock, flags);
 480         if ((gpt->wdt_mode & MPC52xx_GPT_IS_WDT) != 0) {
 481                 raw_spin_unlock_irqrestore(&gpt->lock, flags);
 482                 return -EBUSY;
 483         }
 484
 485         clrbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_COUNTER_ENABLE);
 486         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 487         return 0;
 488 }
 489 EXPORT_SYMBOL(mpc52xx_gpt_stop_timer);
 490
 491 /**
 492  * mpc52xx_gpt_timer_period - Read the timer period
 493  * @gpt: Pointer to gpt private data structure
 494  *
 495  * Returns the timer period in ns
 496  */
 497 u64 mpc52xx_gpt_timer_period(struct mpc52xx_gpt_priv *gpt)
 498 {
 499         u64 period;
 500         u64 prescale;
 501         unsigned long flags;
 502
 503         raw_spin_lock_irqsave(&gpt->lock, flags);
 504         period = in_be32(&gpt->regs->count);
 505         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 506
 507         prescale = period >> 16;
 508         period &= 0xffff;
 509         if (prescale == 0)
 510                 prescale = 0x10000;
 511         period = period * prescale * 1000000000ULL;
 512         do_div(period, (u64)gpt->ipb_freq);
 513         return period;
 514 }
 515 EXPORT_SYMBOL(mpc52xx_gpt_timer_period);
 516
 517 #if defined(CONFIG_MPC5200_WDT)
 518 /***********************************************************************
 519  * Watchdog API for gpt0
 520  */
 521
 522 #define WDT_IDENTITY        "mpc52xx watchdog on GPT0"
 523
 524 /* wdt_is_active stores whether or not the /dev/watchdog device is opened */
 525 static unsigned long wdt_is_active;
 526
 527 /* wdt-capable gpt */
 528 static struct mpc52xx_gpt_priv *mpc52xx_gpt_wdt;
 529
 530 /* low-level wdt functions */
 531 static inline void mpc52xx_gpt_wdt_ping(struct mpc52xx_gpt_priv *gpt_wdt)
 532 {
 533         unsigned long flags;
 534
 535         raw_spin_lock_irqsave(&gpt_wdt->lock, flags);
 536         out_8((u8 *) &gpt_wdt->regs->mode, MPC52xx_GPT_MODE_WDT_PING);
 537         raw_spin_unlock_irqrestore(&gpt_wdt->lock, flags);
 538 }
 539
 540 /* wdt misc device api */
 541 static ssize_t mpc52xx_wdt_write(struct file *file, const char __user *data,
 542                                  size_t len, loff_t *ppos)
 543 {
 544         struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
 545         mpc52xx_gpt_wdt_ping(gpt_wdt);
 546         return 0;
 547 }
 548
 549 static const struct watchdog_info mpc5200_wdt_info = {
 550         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 551         .identity       = WDT_IDENTITY,
 552 };
 553
 554 static long mpc52xx_wdt_ioctl(struct file *file, unsigned int cmd,
 555                               unsigned long arg)
 556 {
 557         struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
 558         int __user *data = (int __user *)arg;
 559         int timeout;
 560         u64 real_timeout;
 561         int ret = 0;
 562
 563         switch (cmd) {
 564         case WDIOC_GETSUPPORT:
 565                 ret = copy_to_user(data, &mpc5200_wdt_info,
 566                                    sizeof(mpc5200_wdt_info));
 567                 if (ret)
 568                         ret = -EFAULT;
 569                 break;
 570
 571         case WDIOC_GETSTATUS:
 572         case WDIOC_GETBOOTSTATUS:
 573                 ret = put_user(0, data);
 574                 break;
 575
 576         case WDIOC_KEEPALIVE:
 577                 mpc52xx_gpt_wdt_ping(gpt_wdt);
 578                 break;
 579
 580         case WDIOC_SETTIMEOUT:
 581                 ret = get_user(timeout, data);
 582                 if (ret)
 583                         break;
 584                 real_timeout = (u64) timeout * 1000000000ULL;
 585                 ret = mpc52xx_gpt_do_start(gpt_wdt, real_timeout, 0, 1);
 586                 if (ret)
 587                         break;
 588                 /* fall through and return the timeout */
 589
 590         case WDIOC_GETTIMEOUT:
 591                 /* we need to round here as to avoid e.g. the following
 592                  * situation:
 593                  * - timeout requested is 1 second;
 594                  * - real timeout @33MHz is 999997090ns
 595                  * - the int divide by 10^9 will return 0.
 596                  */
 597                 real_timeout =
 598                         mpc52xx_gpt_timer_period(gpt_wdt) + 500000000ULL;
 599                 do_div(real_timeout, 1000000000ULL);
 600                 timeout = (int) real_timeout;
 601                 ret = put_user(timeout, data);
 602                 break;
 603
 604         default:
 605                 ret = -ENOTTY;
 606         }
 607         return ret;
 608 }
 609
 610 static int mpc52xx_wdt_open(struct inode *inode, struct file *file)
 611 {
 612         int ret;
 613
 614         /* sanity check */
 615         if (!mpc52xx_gpt_wdt)
 616                 return -ENODEV;
 617
 618         /* /dev/watchdog can only be opened once */
 619         if (test_and_set_bit(0, &wdt_is_active))
 620                 return -EBUSY;
 621
 622         /* Set and activate the watchdog with 30 seconds timeout */
 623         ret = mpc52xx_gpt_do_start(mpc52xx_gpt_wdt, 30ULL * 1000000000ULL,
 624                                    0, 1);
 625         if (ret) {
 626                 clear_bit(0, &wdt_is_active);
 627                 return ret;
 628         }
 629
 630         file->private_data = mpc52xx_gpt_wdt;
 631         return nonseekable_open(inode, file);
 632 }
 633
 634 static int mpc52xx_wdt_release(struct inode *inode, struct file *file)
 635 {
 636         /* note: releasing the wdt in NOWAYOUT-mode does not stop it */
 637 #if !defined(CONFIG_WATCHDOG_NOWAYOUT)
 638         struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
 639         unsigned long flags;
 640
 641         raw_spin_lock_irqsave(&gpt_wdt->lock, flags);
 642         clrbits32(&gpt_wdt->regs->mode,
 643                   MPC52xx_GPT_MODE_COUNTER_ENABLE | MPC52xx_GPT_MODE_WDT_EN);
 644         gpt_wdt->wdt_mode &= ~MPC52xx_GPT_IS_WDT;
 645         raw_spin_unlock_irqrestore(&gpt_wdt->lock, flags);
 646 #endif
 647         clear_bit(0, &wdt_is_active);
 648         return 0;
 649 }
 650
 651
 652 static const struct file_operations mpc52xx_wdt_fops = {
 653         .owner          = THIS_MODULE,
 654         .llseek         = no_llseek,
 655         .write          = mpc52xx_wdt_write,
 656         .unlocked_ioctl = mpc52xx_wdt_ioctl,
 657         .open           = mpc52xx_wdt_open,
 658         .release        = mpc52xx_wdt_release,
 659 };
 660
 661 static struct miscdevice mpc52xx_wdt_miscdev = {
 662         .minor          = WATCHDOG_MINOR,
 663         .name           = "watchdog",
 664         .fops           = &mpc52xx_wdt_fops,
 665 };
 666
 667 static int mpc52xx_gpt_wdt_init(void)
 668 {
 669         int err;
 670
 671         /* try to register the watchdog misc device */
 672         err = misc_register(&mpc52xx_wdt_miscdev);
 673         if (err)
 674                 pr_err("%s: cannot register watchdog device\n", WDT_IDENTITY);
 675         else
 676                 pr_info("%s: watchdog device registered\n", WDT_IDENTITY);
 677         return err;
 678 }
 679
 680 static int mpc52xx_gpt_wdt_setup(struct mpc52xx_gpt_priv *gpt,
 681                                  const u32 *period)
 682 {
 683         u64 real_timeout;
 684
 685         /* remember the gpt for the wdt operation */
 686         mpc52xx_gpt_wdt = gpt;
 687
 688         /* configure the wdt if the device tree contained a timeout */
 689         if (!period || *period == 0)
 690                 return 0;
 691
 692         real_timeout = (u64) *period * 1000000000ULL;
 693         if (mpc52xx_gpt_do_start(gpt, real_timeout, 0, 1))
 694                 dev_warn(gpt->dev, "starting as wdt failed\n");
 695         else
 696                 dev_info(gpt->dev, "watchdog set to %us timeout\n", *period);
 697         return 0;
 698 }
 699
 700 #else
 701
 702 static int mpc52xx_gpt_wdt_init(void)
 703 {
 704         return 0;
 705 }
 706
 707 static inline int mpc52xx_gpt_wdt_setup(struct mpc52xx_gpt_priv *gpt,
 708                                         const u32 *period)
 709 {
 710         return 0;
 711 }
 712
 713 #endif  /*  CONFIG_MPC5200_WDT  */
 714
 715 /* ---------------------------------------------------------------------
 716  * of_platform bus binding code
 717  */
 718 static int mpc52xx_gpt_probe(struct platform_device *ofdev)
 719 {
 720         struct mpc52xx_gpt_priv *gpt;
 721
 722         gpt = devm_kzalloc(&ofdev->dev, sizeof *gpt, GFP_KERNEL);
 723         if (!gpt)
 724                 return -ENOMEM;
 725
 726         raw_spin_lock_init(&gpt->lock);
 727         gpt->dev = &ofdev->dev;
 728         gpt->ipb_freq = mpc5xxx_get_bus_frequency(ofdev->dev.of_node);
 729         gpt->regs = of_iomap(ofdev->dev.of_node, 0);
 730         if (!gpt->regs)
 731                 return -ENOMEM;
 732
 733         dev_set_drvdata(&ofdev->dev, gpt);
 734
 735         mpc52xx_gpt_gpio_setup(gpt, ofdev->dev.of_node);
 736         mpc52xx_gpt_irq_setup(gpt, ofdev->dev.of_node);
 737
 738         mutex_lock(&mpc52xx_gpt_list_mutex);
 739         list_add(&gpt->list, &mpc52xx_gpt_list);
 740         mutex_unlock(&mpc52xx_gpt_list_mutex);
 741
 742         /* check if this device could be a watchdog */
 743         if (of_get_property(ofdev->dev.of_node, "fsl,has-wdt", NULL) ||
 744             of_get_property(ofdev->dev.of_node, "has-wdt", NULL)) {
 745                 const u32 *on_boot_wdt;
 746
 747                 gpt->wdt_mode = MPC52xx_GPT_CAN_WDT;
 748                 on_boot_wdt = of_get_property(ofdev->dev.of_node,
 749                                               "fsl,wdt-on-boot", NULL);
 750                 if (on_boot_wdt) {
 751                         dev_info(gpt->dev, "used as watchdog\n");
 752                         gpt->wdt_mode |= MPC52xx_GPT_IS_WDT;
 753                 } else
 754                         dev_info(gpt->dev, "can function as watchdog\n");
 755                 mpc52xx_gpt_wdt_setup(gpt, on_boot_wdt);
 756         }
 757
 758         return 0;
 759 }
 760
 761 static int mpc52xx_gpt_remove(struct platform_device *ofdev)
 762 {
 763         return -EBUSY;
 764 }
 765
 766 static const struct of_device_id mpc52xx_gpt_match[] = {
 767         { .compatible = "fsl,mpc5200-gpt", },
 768
 769         /* Depreciated compatible values; don't use for new dts files */
 770         { .compatible = "fsl,mpc5200-gpt-gpio", },
 771         { .compatible = "mpc5200-gpt", },
 772         {}
 773 };
 774
 775 static struct platform_driver mpc52xx_gpt_driver = {
 776         .driver = {
 777                 .name = "mpc52xx-gpt",
 778                 .of_match_table = mpc52xx_gpt_match,
 779         },
 780         .probe = mpc52xx_gpt_probe,
 781         .remove = mpc52xx_gpt_remove,
 782 };
 783
 784 static int __init mpc52xx_gpt_init(void)
 785 {
 786         return platform_driver_register(&mpc52xx_gpt_driver);
 787 }
 788
 789 /* Make sure GPIOs and IRQs get set up before anyone tries to use them */
 790 subsys_initcall(mpc52xx_gpt_init);
 791 device_initcall(mpc52xx_gpt_wdt_init);