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

DEFINITIONS

1. mpc52xx_gpt_irq_unmask
2. mpc52xx_gpt_irq_mask
3. mpc52xx_gpt_irq_ack
4. mpc52xx_gpt_irq_set_type
5. mpc52xx_gpt_irq_cascade
6. mpc52xx_gpt_irq_map
7. mpc52xx_gpt_irq_xlate
8. mpc52xx_gpt_irq_setup
9. mpc52xx_gpt_gpio_get
10. mpc52xx_gpt_gpio_set
11. mpc52xx_gpt_gpio_dir_in
12. mpc52xx_gpt_gpio_dir_out
13. mpc52xx_gpt_gpio_setup
14. mpc52xx_gpt_gpio_setup
15. mpc52xx_gpt_from_irq
16. mpc52xx_gpt_do_start
17. mpc52xx_gpt_start_timer
18. mpc52xx_gpt_stop_timer
19. mpc52xx_gpt_timer_period
20. mpc52xx_gpt_wdt_ping
21. mpc52xx_wdt_write
22. mpc52xx_wdt_ioctl
23. mpc52xx_wdt_open
24. mpc52xx_wdt_release
25. mpc52xx_gpt_wdt_init
26. mpc52xx_gpt_wdt_setup
27. mpc52xx_gpt_wdt_init
28. mpc52xx_gpt_wdt_setup
29. mpc52xx_gpt_probe
30. mpc52xx_gpt_remove
31. mpc52xx_gpt_init

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * MPC5200 General Purpose Timer device driver
   4  *
   5  * Copyright (c) 2009 Secret Lab Technologies Ltd.
   6  * Copyright (c) 2008 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
   7  *
   8  * This file is a driver for the the General Purpose Timer (gpt) devices
   9  * found on the MPC5200 SoC.  Each timer has an IO pin which can be used
  10  * for GPIO or can be used to raise interrupts.  The timer function can
  11  * be used independently from the IO pin, or it can be used to control
  12  * output signals or measure input signals.
  13  *
  14  * This driver supports the GPIO and IRQ controller functions of the GPT
  15  * device.  Timer functions are not yet supported.
  16  *
  17  * The timer gpt0 can be used as watchdog (wdt).  If the wdt mode is used,
  18  * this prevents the use of any gpt0 gpt function (i.e. they will fail with
  19  * -EBUSY).  Thus, the safety wdt function always has precedence over the gpt
  20  * function.  If the kernel has been compiled with CONFIG_WATCHDOG_NOWAYOUT,
  21  * this means that gpt0 is locked in wdt mode until the next reboot - this
  22  * may be a requirement in safety applications.
  23  *
  24  * To use the GPIO function, the following two properties must be added
  25  * to the device tree node for the gpt device (typically in the .dts file
  26  * for the board):
  27  *      gpio-controller;
  28  *      #gpio-cells = < 2 >;
  29  * This driver will register the GPIO pin if it finds the gpio-controller
  30  * property in the device tree.
  31  *
  32  * To use the IRQ controller function, the following two properties must
  33  * be added to the device tree node for the gpt device:
  34  *      interrupt-controller;
  35  *      #interrupt-cells = < 1 >;
  36  * The IRQ controller binding only uses one cell to specify the interrupt,
  37  * and the IRQ flags are encoded in the cell.  A cell is not used to encode
  38  * the IRQ number because the GPT only has a single IRQ source.  For flags,
  39  * a value of '1' means rising edge sensitive and '2' means falling edge.
  40  *
  41  * The GPIO and the IRQ controller functions can be used at the same time,
  42  * but in this use case the IO line will only work as an input.  Trying to
  43  * use it as a GPIO output will not work.
  44  *
  45  * When using the GPIO line as an output, it can either be driven as normal
  46  * IO, or it can be an Open Collector (OC) output.  At the moment it is the
  47  * responsibility of either the bootloader or the platform setup code to set
  48  * the output mode.  This driver does not change the output mode setting.
  49  */
  50 
  51 #include <linux/device.h>
  52 #include <linux/irq.h>
  53 #include <linux/interrupt.h>
  54 #include <linux/io.h>
  55 #include <linux/list.h>
  56 #include <linux/mutex.h>
  57 #include <linux/of.h>
  58 #include <linux/of_platform.h>
  59 #include <linux/of_gpio.h>
  60 #include <linux/kernel.h>
  61 #include <linux/slab.h>
  62 #include <linux/fs.h>
  63 #include <linux/watchdog.h>
  64 #include <linux/miscdevice.h>
  65 #include <linux/uaccess.h>
  66 #include <linux/module.h>
  67 #include <asm/div64.h>
  68 #include <asm/mpc52xx.h>
  69 
  70 MODULE_DESCRIPTION("Freescale MPC52xx gpt driver");
  71 MODULE_AUTHOR("Sascha Hauer, Grant Likely, Albrecht Dreß");
  72 MODULE_LICENSE("GPL");
  73 
  74 /**
  75  * struct mpc52xx_gpt - Private data structure for MPC52xx GPT driver
  76  * @dev: pointer to device structure
  77  * @regs: virtual address of GPT registers
  78  * @lock: spinlock to coordinate between different functions.
  79  * @gc: gpio_chip instance structure; used when GPIO is enabled
  80  * @irqhost: Pointer to irq_domain instance; used when IRQ mode is supported
  81  * @wdt_mode: only relevant for gpt0: bit 0 (MPC52xx_GPT_CAN_WDT) indicates
  82  *   if the gpt may be used as wdt, bit 1 (MPC52xx_GPT_IS_WDT) indicates
  83  *   if the timer is actively used as wdt which blocks gpt functions
  84  */
  85 struct mpc52xx_gpt_priv {
  86         struct list_head list;          /* List of all GPT devices */
  87         struct device *dev;
  88         struct mpc52xx_gpt __iomem *regs;
  89         raw_spinlock_t lock;
  90         struct irq_domain *irqhost;
  91         u32 ipb_freq;
  92         u8 wdt_mode;
  93 
  94 #if defined(CONFIG_GPIOLIB)
  95         struct gpio_chip gc;
  96 #endif
  97 };
  98 
  99 LIST_HEAD(mpc52xx_gpt_list);
 100 DEFINE_MUTEX(mpc52xx_gpt_list_mutex);
 101 
 102 #define MPC52xx_GPT_MODE_MS_MASK        (0x07)
 103 #define MPC52xx_GPT_MODE_MS_IC          (0x01)
 104 #define MPC52xx_GPT_MODE_MS_OC          (0x02)
 105 #define MPC52xx_GPT_MODE_MS_PWM         (0x03)
 106 #define MPC52xx_GPT_MODE_MS_GPIO        (0x04)
 107 
 108 #define MPC52xx_GPT_MODE_GPIO_MASK      (0x30)
 109 #define MPC52xx_GPT_MODE_GPIO_OUT_LOW   (0x20)
 110 #define MPC52xx_GPT_MODE_GPIO_OUT_HIGH  (0x30)
 111 
 112 #define MPC52xx_GPT_MODE_COUNTER_ENABLE (0x1000)
 113 #define MPC52xx_GPT_MODE_CONTINUOUS     (0x0400)
 114 #define MPC52xx_GPT_MODE_OPEN_DRAIN     (0x0200)
 115 #define MPC52xx_GPT_MODE_IRQ_EN         (0x0100)
 116 #define MPC52xx_GPT_MODE_WDT_EN         (0x8000)
 117 
 118 #define MPC52xx_GPT_MODE_ICT_MASK       (0x030000)
 119 #define MPC52xx_GPT_MODE_ICT_RISING     (0x010000)
 120 #define MPC52xx_GPT_MODE_ICT_FALLING    (0x020000)
 121 #define MPC52xx_GPT_MODE_ICT_TOGGLE     (0x030000)
 122 
 123 #define MPC52xx_GPT_MODE_WDT_PING       (0xa5)
 124 
 125 #define MPC52xx_GPT_STATUS_IRQMASK      (0x000f)
 126 
 127 #define MPC52xx_GPT_CAN_WDT             (1 << 0)
 128 #define MPC52xx_GPT_IS_WDT              (1 << 1)
 129 
 130 
 131 /* ---------------------------------------------------------------------
 132  * Cascaded interrupt controller hooks
 133  */
 134 
 135 static void mpc52xx_gpt_irq_unmask(struct irq_data *d)
 136 {
 137         struct mpc52xx_gpt_priv *gpt = irq_data_get_irq_chip_data(d);
 138         unsigned long flags;
 139 
 140         raw_spin_lock_irqsave(&gpt->lock, flags);
 141         setbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_IRQ_EN);
 142         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 143 }
 144 
 145 static void mpc52xx_gpt_irq_mask(struct irq_data *d)
 146 {
 147         struct mpc52xx_gpt_priv *gpt = irq_data_get_irq_chip_data(d);
 148         unsigned long flags;
 149 
 150         raw_spin_lock_irqsave(&gpt->lock, flags);
 151         clrbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_IRQ_EN);
 152         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 153 }
 154 
 155 static void mpc52xx_gpt_irq_ack(struct irq_data *d)
 156 {
 157         struct mpc52xx_gpt_priv *gpt = irq_data_get_irq_chip_data(d);
 158 
 159         out_be32(&gpt->regs->status, MPC52xx_GPT_STATUS_IRQMASK);
 160 }
 161 
 162 static int mpc52xx_gpt_irq_set_type(struct irq_data *d, unsigned int flow_type)
 163 {
 164         struct mpc52xx_gpt_priv *gpt = irq_data_get_irq_chip_data(d);
 165         unsigned long flags;
 166         u32 reg;
 167 
 168         dev_dbg(gpt->dev, "%s: virq=%i type=%x\n", __func__, d->irq, flow_type);
 169 
 170         raw_spin_lock_irqsave(&gpt->lock, flags);
 171         reg = in_be32(&gpt->regs->mode) & ~MPC52xx_GPT_MODE_ICT_MASK;
 172         if (flow_type & IRQF_TRIGGER_RISING)
 173                 reg |= MPC52xx_GPT_MODE_ICT_RISING;
 174         if (flow_type & IRQF_TRIGGER_FALLING)
 175                 reg |= MPC52xx_GPT_MODE_ICT_FALLING;
 176         out_be32(&gpt->regs->mode, reg);
 177         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 178 
 179         return 0;
 180 }
 181 
 182 static struct irq_chip mpc52xx_gpt_irq_chip = {
 183         .name = "MPC52xx GPT",
 184         .irq_unmask = mpc52xx_gpt_irq_unmask,
 185         .irq_mask = mpc52xx_gpt_irq_mask,
 186         .irq_ack = mpc52xx_gpt_irq_ack,
 187         .irq_set_type = mpc52xx_gpt_irq_set_type,
 188 };
 189 
 190 static void mpc52xx_gpt_irq_cascade(struct irq_desc *desc)
 191 {
 192         struct mpc52xx_gpt_priv *gpt = irq_desc_get_handler_data(desc);
 193         int sub_virq;
 194         u32 status;
 195 
 196         status = in_be32(&gpt->regs->status) & MPC52xx_GPT_STATUS_IRQMASK;
 197         if (status) {
 198                 sub_virq = irq_linear_revmap(gpt->irqhost, 0);
 199                 generic_handle_irq(sub_virq);
 200         }
 201 }
 202 
 203 static int mpc52xx_gpt_irq_map(struct irq_domain *h, unsigned int virq,
 204                                irq_hw_number_t hw)
 205 {
 206         struct mpc52xx_gpt_priv *gpt = h->host_data;
 207 
 208         dev_dbg(gpt->dev, "%s: h=%p, virq=%i\n", __func__, h, virq);
 209         irq_set_chip_data(virq, gpt);
 210         irq_set_chip_and_handler(virq, &mpc52xx_gpt_irq_chip, handle_edge_irq);
 211 
 212         return 0;
 213 }
 214 
 215 static int mpc52xx_gpt_irq_xlate(struct irq_domain *h, struct device_node *ct,
 216                                  const u32 *intspec, unsigned int intsize,
 217                                  irq_hw_number_t *out_hwirq,
 218                                  unsigned int *out_flags)
 219 {
 220         struct mpc52xx_gpt_priv *gpt = h->host_data;
 221 
 222         dev_dbg(gpt->dev, "%s: flags=%i\n", __func__, intspec[0]);
 223 
 224         if ((intsize < 1) || (intspec[0] > 3)) {
 225                 dev_err(gpt->dev, "bad irq specifier in %pOF\n", ct);
 226                 return -EINVAL;
 227         }
 228 
 229         *out_hwirq = 0; /* The GPT only has 1 IRQ line */
 230         *out_flags = intspec[0];
 231 
 232         return 0;
 233 }
 234 
 235 static const struct irq_domain_ops mpc52xx_gpt_irq_ops = {
 236         .map = mpc52xx_gpt_irq_map,
 237         .xlate = mpc52xx_gpt_irq_xlate,
 238 };
 239 
 240 static void
 241 mpc52xx_gpt_irq_setup(struct mpc52xx_gpt_priv *gpt, struct device_node *node)
 242 {
 243         int cascade_virq;
 244         unsigned long flags;
 245         u32 mode;
 246 
 247         cascade_virq = irq_of_parse_and_map(node, 0);
 248         if (!cascade_virq)
 249                 return;
 250 
 251         gpt->irqhost = irq_domain_add_linear(node, 1, &mpc52xx_gpt_irq_ops, gpt);
 252         if (!gpt->irqhost) {
 253                 dev_err(gpt->dev, "irq_domain_add_linear() failed\n");
 254                 return;
 255         }
 256 
 257         irq_set_handler_data(cascade_virq, gpt);
 258         irq_set_chained_handler(cascade_virq, mpc52xx_gpt_irq_cascade);
 259 
 260         /* If the GPT is currently disabled, then change it to be in Input
 261          * Capture mode.  If the mode is non-zero, then the pin could be
 262          * already in use for something. */
 263         raw_spin_lock_irqsave(&gpt->lock, flags);
 264         mode = in_be32(&gpt->regs->mode);
 265         if ((mode & MPC52xx_GPT_MODE_MS_MASK) == 0)
 266                 out_be32(&gpt->regs->mode, mode | MPC52xx_GPT_MODE_MS_IC);
 267         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 268 
 269         dev_dbg(gpt->dev, "%s() complete. virq=%i\n", __func__, cascade_virq);
 270 }
 271 
 272 
 273 /* ---------------------------------------------------------------------
 274  * GPIOLIB hooks
 275  */
 276 #if defined(CONFIG_GPIOLIB)
 277 static int mpc52xx_gpt_gpio_get(struct gpio_chip *gc, unsigned int gpio)
 278 {
 279         struct mpc52xx_gpt_priv *gpt = gpiochip_get_data(gc);
 280 
 281         return (in_be32(&gpt->regs->status) >> 8) & 1;
 282 }
 283 
 284 static void
 285 mpc52xx_gpt_gpio_set(struct gpio_chip *gc, unsigned int gpio, int v)
 286 {
 287         struct mpc52xx_gpt_priv *gpt = gpiochip_get_data(gc);
 288         unsigned long flags;
 289         u32 r;
 290 
 291         dev_dbg(gpt->dev, "%s: gpio:%d v:%d\n", __func__, gpio, v);
 292         r = v ? MPC52xx_GPT_MODE_GPIO_OUT_HIGH : MPC52xx_GPT_MODE_GPIO_OUT_LOW;
 293 
 294         raw_spin_lock_irqsave(&gpt->lock, flags);
 295         clrsetbits_be32(&gpt->regs->mode, MPC52xx_GPT_MODE_GPIO_MASK, r);
 296         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 297 }
 298 
 299 static int mpc52xx_gpt_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
 300 {
 301         struct mpc52xx_gpt_priv *gpt = gpiochip_get_data(gc);
 302         unsigned long flags;
 303 
 304         dev_dbg(gpt->dev, "%s: gpio:%d\n", __func__, gpio);
 305 
 306         raw_spin_lock_irqsave(&gpt->lock, flags);
 307         clrbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_GPIO_MASK);
 308         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 309 
 310         return 0;
 311 }
 312 
 313 static int
 314 mpc52xx_gpt_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
 315 {
 316         mpc52xx_gpt_gpio_set(gc, gpio, val);
 317         return 0;
 318 }
 319 
 320 static void
 321 mpc52xx_gpt_gpio_setup(struct mpc52xx_gpt_priv *gpt, struct device_node *node)
 322 {
 323         int rc;
 324 
 325         /* Only setup GPIO if the device tree claims the GPT is
 326          * a GPIO controller */
 327         if (!of_find_property(node, "gpio-controller", NULL))
 328                 return;
 329 
 330         gpt->gc.label = kasprintf(GFP_KERNEL, "%pOF", node);
 331         if (!gpt->gc.label) {
 332                 dev_err(gpt->dev, "out of memory\n");
 333                 return;
 334         }
 335 
 336         gpt->gc.ngpio = 1;
 337         gpt->gc.direction_input  = mpc52xx_gpt_gpio_dir_in;
 338         gpt->gc.direction_output = mpc52xx_gpt_gpio_dir_out;
 339         gpt->gc.get = mpc52xx_gpt_gpio_get;
 340         gpt->gc.set = mpc52xx_gpt_gpio_set;
 341         gpt->gc.base = -1;
 342         gpt->gc.of_node = node;
 343 
 344         /* Setup external pin in GPIO mode */
 345         clrsetbits_be32(&gpt->regs->mode, MPC52xx_GPT_MODE_MS_MASK,
 346                         MPC52xx_GPT_MODE_MS_GPIO);
 347 
 348         rc = gpiochip_add_data(&gpt->gc, gpt);
 349         if (rc)
 350                 dev_err(gpt->dev, "gpiochip_add_data() failed; rc=%i\n", rc);
 351 
 352         dev_dbg(gpt->dev, "%s() complete.\n", __func__);
 353 }
 354 #else /* defined(CONFIG_GPIOLIB) */
 355 static void
 356 mpc52xx_gpt_gpio_setup(struct mpc52xx_gpt_priv *p, struct device_node *np) { }
 357 #endif /* defined(CONFIG_GPIOLIB) */
 358 
 359 /***********************************************************************
 360  * Timer API
 361  */
 362 
 363 /**
 364  * mpc52xx_gpt_from_irq - Return the GPT device associated with an IRQ number
 365  * @irq: irq of timer.
 366  */
 367 struct mpc52xx_gpt_priv *mpc52xx_gpt_from_irq(int irq)
 368 {
 369         struct mpc52xx_gpt_priv *gpt;
 370         struct list_head *pos;
 371 
 372         /* Iterate over the list of timers looking for a matching device */
 373         mutex_lock(&mpc52xx_gpt_list_mutex);
 374         list_for_each(pos, &mpc52xx_gpt_list) {
 375                 gpt = container_of(pos, struct mpc52xx_gpt_priv, list);
 376                 if (gpt->irqhost && irq == irq_linear_revmap(gpt->irqhost, 0)) {
 377                         mutex_unlock(&mpc52xx_gpt_list_mutex);
 378                         return gpt;
 379                 }
 380         }
 381         mutex_unlock(&mpc52xx_gpt_list_mutex);
 382 
 383         return NULL;
 384 }
 385 EXPORT_SYMBOL(mpc52xx_gpt_from_irq);
 386 
 387 static int mpc52xx_gpt_do_start(struct mpc52xx_gpt_priv *gpt, u64 period,
 388                                 int continuous, int as_wdt)
 389 {
 390         u32 clear, set;
 391         u64 clocks;
 392         u32 prescale;
 393         unsigned long flags;
 394 
 395         clear = MPC52xx_GPT_MODE_MS_MASK | MPC52xx_GPT_MODE_CONTINUOUS;
 396         set = MPC52xx_GPT_MODE_MS_GPIO | MPC52xx_GPT_MODE_COUNTER_ENABLE;
 397         if (as_wdt) {
 398                 clear |= MPC52xx_GPT_MODE_IRQ_EN;
 399                 set |= MPC52xx_GPT_MODE_WDT_EN;
 400         } else if (continuous)
 401                 set |= MPC52xx_GPT_MODE_CONTINUOUS;
 402 
 403         /* Determine the number of clocks in the requested period.  64 bit
 404          * arithmatic is done here to preserve the precision until the value
 405          * is scaled back down into the u32 range.  Period is in 'ns', bus
 406          * frequency is in Hz. */
 407         clocks = period * (u64)gpt->ipb_freq;
 408         do_div(clocks, 1000000000); /* Scale it down to ns range */
 409 
 410         /* This device cannot handle a clock count greater than 32 bits */
 411         if (clocks > 0xffffffff)
 412                 return -EINVAL;
 413 
 414         /* Calculate the prescaler and count values from the clocks value.
 415          * 'clocks' is the number of clock ticks in the period.  The timer
 416          * has 16 bit precision and a 16 bit prescaler.  Prescaler is
 417          * calculated by integer dividing the clocks by 0x10000 (shifting
 418          * down 16 bits) to obtain the smallest possible divisor for clocks
 419          * to get a 16 bit count value.
 420          *
 421          * Note: the prescale register is '1' based, not '0' based.  ie. a
 422          * value of '1' means divide the clock by one.  0xffff divides the
 423          * clock by 0xffff.  '0x0000' does not divide by zero, but wraps
 424          * around and divides by 0x10000.  That is why prescale must be
 425          * a u32 variable, not a u16, for this calculation. */
 426         prescale = (clocks >> 16) + 1;
 427         do_div(clocks, prescale);
 428         if (clocks > 0xffff) {
 429                 pr_err("calculation error; prescale:%x clocks:%llx\n",
 430                        prescale, clocks);
 431                 return -EINVAL;
 432         }
 433 
 434         /* Set and enable the timer, reject an attempt to use a wdt as gpt */
 435         raw_spin_lock_irqsave(&gpt->lock, flags);
 436         if (as_wdt)
 437                 gpt->wdt_mode |= MPC52xx_GPT_IS_WDT;
 438         else if ((gpt->wdt_mode & MPC52xx_GPT_IS_WDT) != 0) {
 439                 raw_spin_unlock_irqrestore(&gpt->lock, flags);
 440                 return -EBUSY;
 441         }
 442         out_be32(&gpt->regs->count, prescale << 16 | clocks);
 443         clrsetbits_be32(&gpt->regs->mode, clear, set);
 444         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 445 
 446         return 0;
 447 }
 448 
 449 /**
 450  * mpc52xx_gpt_start_timer - Set and enable the GPT timer
 451  * @gpt: Pointer to gpt private data structure
 452  * @period: period of timer in ns; max. ~130s @ 33MHz IPB clock
 453  * @continuous: set to 1 to make timer continuous free running
 454  *
 455  * An interrupt will be generated every time the timer fires
 456  */
 457 int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, u64 period,
 458                             int continuous)
 459 {
 460         return mpc52xx_gpt_do_start(gpt, period, continuous, 0);
 461 }
 462 EXPORT_SYMBOL(mpc52xx_gpt_start_timer);
 463 
 464 /**
 465  * mpc52xx_gpt_stop_timer - Stop a gpt
 466  * @gpt: Pointer to gpt private data structure
 467  *
 468  * Returns an error if attempting to stop a wdt
 469  */
 470 int mpc52xx_gpt_stop_timer(struct mpc52xx_gpt_priv *gpt)
 471 {
 472         unsigned long flags;
 473 
 474         /* reject the operation if the timer is used as watchdog (gpt 0 only) */
 475         raw_spin_lock_irqsave(&gpt->lock, flags);
 476         if ((gpt->wdt_mode & MPC52xx_GPT_IS_WDT) != 0) {
 477                 raw_spin_unlock_irqrestore(&gpt->lock, flags);
 478                 return -EBUSY;
 479         }
 480 
 481         clrbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_COUNTER_ENABLE);
 482         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 483         return 0;
 484 }
 485 EXPORT_SYMBOL(mpc52xx_gpt_stop_timer);
 486 
 487 /**
 488  * mpc52xx_gpt_timer_period - Read the timer period
 489  * @gpt: Pointer to gpt private data structure
 490  *
 491  * Returns the timer period in ns
 492  */
 493 u64 mpc52xx_gpt_timer_period(struct mpc52xx_gpt_priv *gpt)
 494 {
 495         u64 period;
 496         u64 prescale;
 497         unsigned long flags;
 498 
 499         raw_spin_lock_irqsave(&gpt->lock, flags);
 500         period = in_be32(&gpt->regs->count);
 501         raw_spin_unlock_irqrestore(&gpt->lock, flags);
 502 
 503         prescale = period >> 16;
 504         period &= 0xffff;
 505         if (prescale == 0)
 506                 prescale = 0x10000;
 507         period = period * prescale * 1000000000ULL;
 508         do_div(period, (u64)gpt->ipb_freq);
 509         return period;
 510 }
 511 EXPORT_SYMBOL(mpc52xx_gpt_timer_period);
 512 
 513 #if defined(CONFIG_MPC5200_WDT)
 514 /***********************************************************************
 515  * Watchdog API for gpt0
 516  */
 517 
 518 #define WDT_IDENTITY        "mpc52xx watchdog on GPT0"
 519 
 520 /* wdt_is_active stores whether or not the /dev/watchdog device is opened */
 521 static unsigned long wdt_is_active;
 522 
 523 /* wdt-capable gpt */
 524 static struct mpc52xx_gpt_priv *mpc52xx_gpt_wdt;
 525 
 526 /* low-level wdt functions */
 527 static inline void mpc52xx_gpt_wdt_ping(struct mpc52xx_gpt_priv *gpt_wdt)
 528 {
 529         unsigned long flags;
 530 
 531         raw_spin_lock_irqsave(&gpt_wdt->lock, flags);
 532         out_8((u8 *) &gpt_wdt->regs->mode, MPC52xx_GPT_MODE_WDT_PING);
 533         raw_spin_unlock_irqrestore(&gpt_wdt->lock, flags);
 534 }
 535 
 536 /* wdt misc device api */
 537 static ssize_t mpc52xx_wdt_write(struct file *file, const char __user *data,
 538                                  size_t len, loff_t *ppos)
 539 {
 540         struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
 541         mpc52xx_gpt_wdt_ping(gpt_wdt);
 542         return 0;
 543 }
 544 
 545 static const struct watchdog_info mpc5200_wdt_info = {
 546         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 547         .identity       = WDT_IDENTITY,
 548 };
 549 
 550 static long mpc52xx_wdt_ioctl(struct file *file, unsigned int cmd,
 551                               unsigned long arg)
 552 {
 553         struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
 554         int __user *data = (int __user *)arg;
 555         int timeout;
 556         u64 real_timeout;
 557         int ret = 0;
 558 
 559         switch (cmd) {
 560         case WDIOC_GETSUPPORT:
 561                 ret = copy_to_user(data, &mpc5200_wdt_info,
 562                                    sizeof(mpc5200_wdt_info));
 563                 if (ret)
 564                         ret = -EFAULT;
 565                 break;
 566 
 567         case WDIOC_GETSTATUS:
 568         case WDIOC_GETBOOTSTATUS:
 569                 ret = put_user(0, data);
 570                 break;
 571 
 572         case WDIOC_KEEPALIVE:
 573                 mpc52xx_gpt_wdt_ping(gpt_wdt);
 574                 break;
 575 
 576         case WDIOC_SETTIMEOUT:
 577                 ret = get_user(timeout, data);
 578                 if (ret)
 579                         break;
 580                 real_timeout = (u64) timeout * 1000000000ULL;
 581                 ret = mpc52xx_gpt_do_start(gpt_wdt, real_timeout, 0, 1);
 582                 if (ret)
 583                         break;
 584                 /* fall through and return the timeout */
 585 
 586         case WDIOC_GETTIMEOUT:
 587                 /* we need to round here as to avoid e.g. the following
 588                  * situation:
 589                  * - timeout requested is 1 second;
 590                  * - real timeout @33MHz is 999997090ns
 591                  * - the int divide by 10^9 will return 0.
 592                  */
 593                 real_timeout =
 594                         mpc52xx_gpt_timer_period(gpt_wdt) + 500000000ULL;
 595                 do_div(real_timeout, 1000000000ULL);
 596                 timeout = (int) real_timeout;
 597                 ret = put_user(timeout, data);
 598                 break;
 599 
 600         default:
 601                 ret = -ENOTTY;
 602         }
 603         return ret;
 604 }
 605 
 606 static int mpc52xx_wdt_open(struct inode *inode, struct file *file)
 607 {
 608         int ret;
 609 
 610         /* sanity check */
 611         if (!mpc52xx_gpt_wdt)
 612                 return -ENODEV;
 613 
 614         /* /dev/watchdog can only be opened once */
 615         if (test_and_set_bit(0, &wdt_is_active))
 616                 return -EBUSY;
 617 
 618         /* Set and activate the watchdog with 30 seconds timeout */
 619         ret = mpc52xx_gpt_do_start(mpc52xx_gpt_wdt, 30ULL * 1000000000ULL,
 620                                    0, 1);
 621         if (ret) {
 622                 clear_bit(0, &wdt_is_active);
 623                 return ret;
 624         }
 625 
 626         file->private_data = mpc52xx_gpt_wdt;
 627         return stream_open(inode, file);
 628 }
 629 
 630 static int mpc52xx_wdt_release(struct inode *inode, struct file *file)
 631 {
 632         /* note: releasing the wdt in NOWAYOUT-mode does not stop it */
 633 #if !defined(CONFIG_WATCHDOG_NOWAYOUT)
 634         struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
 635         unsigned long flags;
 636 
 637         raw_spin_lock_irqsave(&gpt_wdt->lock, flags);
 638         clrbits32(&gpt_wdt->regs->mode,
 639                   MPC52xx_GPT_MODE_COUNTER_ENABLE | MPC52xx_GPT_MODE_WDT_EN);
 640         gpt_wdt->wdt_mode &= ~MPC52xx_GPT_IS_WDT;
 641         raw_spin_unlock_irqrestore(&gpt_wdt->lock, flags);
 642 #endif
 643         clear_bit(0, &wdt_is_active);
 644         return 0;
 645 }
 646 
 647 
 648 static const struct file_operations mpc52xx_wdt_fops = {
 649         .owner          = THIS_MODULE,
 650         .llseek         = no_llseek,
 651         .write          = mpc52xx_wdt_write,
 652         .unlocked_ioctl = mpc52xx_wdt_ioctl,
 653         .open           = mpc52xx_wdt_open,
 654         .release        = mpc52xx_wdt_release,
 655 };
 656 
 657 static struct miscdevice mpc52xx_wdt_miscdev = {
 658         .minor          = WATCHDOG_MINOR,
 659         .name           = "watchdog",
 660         .fops           = &mpc52xx_wdt_fops,
 661 };
 662 
 663 static int mpc52xx_gpt_wdt_init(void)
 664 {
 665         int err;
 666 
 667         /* try to register the watchdog misc device */
 668         err = misc_register(&mpc52xx_wdt_miscdev);
 669         if (err)
 670                 pr_err("%s: cannot register watchdog device\n", WDT_IDENTITY);
 671         else
 672                 pr_info("%s: watchdog device registered\n", WDT_IDENTITY);
 673         return err;
 674 }
 675 
 676 static int mpc52xx_gpt_wdt_setup(struct mpc52xx_gpt_priv *gpt,
 677                                  const u32 *period)
 678 {
 679         u64 real_timeout;
 680 
 681         /* remember the gpt for the wdt operation */
 682         mpc52xx_gpt_wdt = gpt;
 683 
 684         /* configure the wdt if the device tree contained a timeout */
 685         if (!period || *period == 0)
 686                 return 0;
 687 
 688         real_timeout = (u64) *period * 1000000000ULL;
 689         if (mpc52xx_gpt_do_start(gpt, real_timeout, 0, 1))
 690                 dev_warn(gpt->dev, "starting as wdt failed\n");
 691         else
 692                 dev_info(gpt->dev, "watchdog set to %us timeout\n", *period);
 693         return 0;
 694 }
 695 
 696 #else
 697 
 698 static int mpc52xx_gpt_wdt_init(void)
 699 {
 700         return 0;
 701 }
 702 
 703 static inline int mpc52xx_gpt_wdt_setup(struct mpc52xx_gpt_priv *gpt,
 704                                         const u32 *period)
 705 {
 706         return 0;
 707 }
 708 
 709 #endif  /*  CONFIG_MPC5200_WDT  */
 710 
 711 /* ---------------------------------------------------------------------
 712  * of_platform bus binding code
 713  */
 714 static int mpc52xx_gpt_probe(struct platform_device *ofdev)
 715 {
 716         struct mpc52xx_gpt_priv *gpt;
 717 
 718         gpt = devm_kzalloc(&ofdev->dev, sizeof *gpt, GFP_KERNEL);
 719         if (!gpt)
 720                 return -ENOMEM;
 721 
 722         raw_spin_lock_init(&gpt->lock);
 723         gpt->dev = &ofdev->dev;
 724         gpt->ipb_freq = mpc5xxx_get_bus_frequency(ofdev->dev.of_node);
 725         gpt->regs = of_iomap(ofdev->dev.of_node, 0);
 726         if (!gpt->regs)
 727                 return -ENOMEM;
 728 
 729         dev_set_drvdata(&ofdev->dev, gpt);
 730 
 731         mpc52xx_gpt_gpio_setup(gpt, ofdev->dev.of_node);
 732         mpc52xx_gpt_irq_setup(gpt, ofdev->dev.of_node);
 733 
 734         mutex_lock(&mpc52xx_gpt_list_mutex);
 735         list_add(&gpt->list, &mpc52xx_gpt_list);
 736         mutex_unlock(&mpc52xx_gpt_list_mutex);
 737 
 738         /* check if this device could be a watchdog */
 739         if (of_get_property(ofdev->dev.of_node, "fsl,has-wdt", NULL) ||
 740             of_get_property(ofdev->dev.of_node, "has-wdt", NULL)) {
 741                 const u32 *on_boot_wdt;
 742 
 743                 gpt->wdt_mode = MPC52xx_GPT_CAN_WDT;
 744                 on_boot_wdt = of_get_property(ofdev->dev.of_node,
 745                                               "fsl,wdt-on-boot", NULL);
 746                 if (on_boot_wdt) {
 747                         dev_info(gpt->dev, "used as watchdog\n");
 748                         gpt->wdt_mode |= MPC52xx_GPT_IS_WDT;
 749                 } else
 750                         dev_info(gpt->dev, "can function as watchdog\n");
 751                 mpc52xx_gpt_wdt_setup(gpt, on_boot_wdt);
 752         }
 753 
 754         return 0;
 755 }
 756 
 757 static int mpc52xx_gpt_remove(struct platform_device *ofdev)
 758 {
 759         return -EBUSY;
 760 }
 761 
 762 static const struct of_device_id mpc52xx_gpt_match[] = {
 763         { .compatible = "fsl,mpc5200-gpt", },
 764 
 765         /* Depreciated compatible values; don't use for new dts files */
 766         { .compatible = "fsl,mpc5200-gpt-gpio", },
 767         { .compatible = "mpc5200-gpt", },
 768         {}
 769 };
 770 
 771 static struct platform_driver mpc52xx_gpt_driver = {
 772         .driver = {
 773                 .name = "mpc52xx-gpt",
 774                 .of_match_table = mpc52xx_gpt_match,
 775         },
 776         .probe = mpc52xx_gpt_probe,
 777         .remove = mpc52xx_gpt_remove,
 778 };
 779 
 780 static int __init mpc52xx_gpt_init(void)
 781 {
 782         return platform_driver_register(&mpc52xx_gpt_driver);
 783 }
 784 
 785 /* Make sure GPIOs and IRQs get set up before anyone tries to use them */
 786 subsys_initcall(mpc52xx_gpt_init);
 787 device_initcall(mpc52xx_gpt_wdt_init);