1 files changed, 107 insertions, 16 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d8db2f8ee411..24c62b848bf9 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -43,6 +43,7 @@ struct gpio_desc {
 /* flag symbols are bit numbers */
 #define FLAG_REQUESTED  0
 #define FLAG_IS_OUT     1
+#define FLAG_RESERVED   2
 
 #ifdef CONFIG_DEBUG_FS
         const char              *label;
@@ -68,6 +69,9 @@ static void gpio_ensure_requested(struct gpio_desc *desc)
         if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
                 pr_warning("GPIO-%d autorequested\n", (int)(desc - gpio_desc));
                 desc_set_label(desc, "[auto]");
+                if (!try_module_get(desc->chip->owner))
+                        pr_err("GPIO-%d: module can't be gotten \n",
+                                        (int)(desc - gpio_desc));
         }
 }
 
@@ -77,6 +81,76 @@ static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
         return gpio_desc[gpio].chip;
 }
 
+/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
+static int gpiochip_find_base(int ngpio)
+{
+        int i;
+        int spare = 0;
+        int base = -ENOSPC;
+
+        for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
+                struct gpio_desc *desc = &gpio_desc[i];
+                struct gpio_chip *chip = desc->chip;
+
+                if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
+                        spare++;
+                        if (spare == ngpio) {
+                                base = i;
+                                break;
+                        }
+                } else {
+                        spare = 0;
+                        if (chip)
+                                i -= chip->ngpio - 1;
+                }
+        }
+
+        if (gpio_is_valid(base))
+                pr_debug("%s: found new base at %d\n", __func__, base);
+        return base;
+}
+
+/**
+ * gpiochip_reserve() - reserve range of gpios to use with platform code only
+ * @start: starting gpio number
+ * @ngpio: number of gpios to reserve
+ * Context: platform init, potentially before irqs or kmalloc will work
+ *
+ * Returns a negative errno if any gpio within the range is already reserved
+ * or registered, else returns zero as a success code.  Use this function
+ * to mark a range of gpios as unavailable for dynamic gpio number allocation,
+ * for example because its driver support is not yet loaded.
+ */
+int __init gpiochip_reserve(int start, int ngpio)
+{
+        int ret = 0;
+        unsigned long flags;
+        int i;
+
+        if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio))
+                return -EINVAL;
+
+        spin_lock_irqsave(&gpio_lock, flags);
+
+        for (i = start; i < start + ngpio; i++) {
+                struct gpio_desc *desc = &gpio_desc[i];
+
+                if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
+                        ret = -EBUSY;
+                        goto err;
+                }
+
+                set_bit(FLAG_RESERVED, &desc->flags);
+        }
+
+        pr_debug("%s: reserved gpios from %d to %d\n",
+                 __func__, start, start + ngpio - 1);
+err:
+        spin_unlock_irqrestore(&gpio_lock, flags);
+
+        return ret;
+}
+
 /**
  * gpiochip_add() - register a gpio_chip
  * @chip: the chip to register, with chip->base initialized
@@ -85,38 +159,49 @@ static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
  * Returns a negative errno if the chip can't be registered, such as
  * because the chip->base is invalid or already associated with a
  * different chip.  Otherwise it returns zero as a success code.
+ *
+ * If chip->base is negative, this requests dynamic assignment of
+ * a range of valid GPIOs.
  */
 int gpiochip_add(struct gpio_chip *chip)
 {
         unsigned long   flags;
         int             status = 0;
         unsigned        id;
+        int             base = chip->base;
 
-        /* NOTE chip->base negative is reserved to mean a request for
-         * dynamic allocation.  We don't currently support that.
-         */
-
-        if (chip->base < 0 || (chip->base  + chip->ngpio) >= ARCH_NR_GPIOS) {
+        if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio))
+                        && base >= 0) {
                 status = -EINVAL;
                 goto fail;
         }
 
         spin_lock_irqsave(&gpio_lock, flags);
 
+        if (base < 0) {
+                base = gpiochip_find_base(chip->ngpio);
+                if (base < 0) {
+                        status = base;
+                        goto fail_unlock;
+                }
+                chip->base = base;
+        }
+
         /* these GPIO numbers must not be managed by another gpio_chip */
-        for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+        for (id = base; id < base + chip->ngpio; id++) {
                 if (gpio_desc[id].chip != NULL) {
                         status = -EBUSY;
                         break;
                 }
         }
         if (status == 0) {
-                for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+                for (id = base; id < base + chip->ngpio; id++) {
                         gpio_desc[id].chip = chip;
                         gpio_desc[id].flags = 0;
                 }
         }
 
+fail_unlock:
         spin_unlock_irqrestore(&gpio_lock, flags);
 fail:
         /* failures here can mean systems won't boot... */
@@ -171,12 +256,15 @@ int gpio_request(unsigned gpio, const char *label)
 
         spin_lock_irqsave(&gpio_lock, flags);
 
-        if (gpio >= ARCH_NR_GPIOS)
+        if (!gpio_is_valid(gpio))
                 goto done;
         desc = &gpio_desc[gpio];
         if (desc->chip == NULL)
                 goto done;
 
+        if (!try_module_get(desc->chip->owner))
+                goto done;
+
         /* NOTE:  gpio_request() can be called in early boot,
          * before IRQs are enabled.
          */
@@ -184,8 +272,10 @@ int gpio_request(unsigned gpio, const char *label)
         if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
                 desc_set_label(desc, label ? : "?");
                 status = 0;
-        } else
+        } else {
                 status = -EBUSY;
+                module_put(desc->chip->owner);
+        }
 
 done:
         if (status)
@@ -201,7 +291,7 @@ void gpio_free(unsigned gpio)
         unsigned long           flags;
         struct gpio_desc        *desc;
 
-        if (gpio >= ARCH_NR_GPIOS) {
+        if (!gpio_is_valid(gpio)) {
                 WARN_ON(extra_checks);
                 return;
         }
@@ -209,9 +299,10 @@ void gpio_free(unsigned gpio)
         spin_lock_irqsave(&gpio_lock, flags);
 
         desc = &gpio_desc[gpio];
-        if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags))
+        if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags)) {
                 desc_set_label(desc, NULL);
-        else
+                module_put(desc->chip->owner);
+        } else
                 WARN_ON(extra_checks);
 
         spin_unlock_irqrestore(&gpio_lock, flags);
@@ -236,7 +327,7 @@ const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
 {
         unsigned gpio = chip->base + offset;
 
-        if (gpio >= ARCH_NR_GPIOS || gpio_desc[gpio].chip != chip)
+        if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip)
                 return NULL;
         if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
                 return NULL;
@@ -267,7 +358,7 @@ int gpio_direction_input(unsigned gpio)
 
         spin_lock_irqsave(&gpio_lock, flags);
 
-        if (gpio >= ARCH_NR_GPIOS)
+        if (!gpio_is_valid(gpio))
                 goto fail;
         chip = desc->chip;
         if (!chip || !chip->get || !chip->direction_input)
@@ -305,7 +396,7 @@ int gpio_direction_output(unsigned gpio, int value)
 
         spin_lock_irqsave(&gpio_lock, flags);
 
-        if (gpio >= ARCH_NR_GPIOS)
+        if (!gpio_is_valid(gpio))
                 goto fail;
         chip = desc->chip;
         if (!chip || !chip->set || !chip->direction_output)
@@ -522,7 +613,7 @@ static int gpiolib_show(struct seq_file *s, void *unused)
 
         /* REVISIT this isn't locked against gpio_chip removal ... */
 
-        for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
+        for (gpio = 0; gpio_is_valid(gpio); gpio++) {
                 if (chip == gpio_desc[gpio].chip)
                         continue;
                 chip = gpio_desc[gpio].chip;