1 files changed, 205 insertions, 1 deletions

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 10b8af27e03a..b3ac6c5bc5c6 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -3,6 +3,7 @@
  *
  *  Copyright (C) 2003 Russell King, All Rights Reserved.
  *  Copyright (C) 2007-2008 Pierre Ossman
+ *  Copyright (C) 2010 Linus Walleij
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -20,6 +21,7 @@
 #include <linux/suspend.h>
 
 #include <linux/mmc/host.h>
+#include <linux/mmc/card.h>
 
 #include "core.h"
 #include "host.h"
@@ -50,6 +52,205 @@ void mmc_unregister_host_class(void)
 static DEFINE_IDR(mmc_host_idr);
 static DEFINE_SPINLOCK(mmc_host_lock);
 
+#ifdef CONFIG_MMC_CLKGATE
+
+/*
+ * Enabling clock gating will make the core call out to the host
+ * once up and once down when it performs a request or card operation
+ * intermingled in any fashion. The driver will see this through
+ * set_ios() operations with ios.clock field set to 0 to gate (disable)
+ * the block clock, and to the old frequency to enable it again.
+ */
+static void mmc_host_clk_gate_delayed(struct mmc_host *host)
+{
+        unsigned long tick_ns;
+        unsigned long freq = host->ios.clock;
+        unsigned long flags;
+
+        if (!freq) {
+                pr_debug("%s: frequency set to 0 in disable function, "
+                         "this means the clock is already disabled.\n",
+                         mmc_hostname(host));
+                return;
+        }
+        /*
+         * New requests may have appeared while we were scheduling,
+         * then there is no reason to delay the check before
+         * clk_disable().
+         */
+        spin_lock_irqsave(&host->clk_lock, flags);
+
+        /*
+         * Delay n bus cycles (at least 8 from MMC spec) before attempting
+         * to disable the MCI block clock. The reference count may have
+         * gone up again after this delay due to rescheduling!
+         */
+        if (!host->clk_requests) {
+                spin_unlock_irqrestore(&host->clk_lock, flags);
+                tick_ns = DIV_ROUND_UP(1000000000, freq);
+                ndelay(host->clk_delay * tick_ns);
+        } else {
+                /* New users appeared while waiting for this work */
+                spin_unlock_irqrestore(&host->clk_lock, flags);
+                return;
+        }
+        mutex_lock(&host->clk_gate_mutex);
+        spin_lock_irqsave(&host->clk_lock, flags);
+        if (!host->clk_requests) {
+                spin_unlock_irqrestore(&host->clk_lock, flags);
+                /* This will set host->ios.clock to 0 */
+                mmc_gate_clock(host);
+                spin_lock_irqsave(&host->clk_lock, flags);
+                pr_debug("%s: gated MCI clock\n", mmc_hostname(host));
+        }
+        spin_unlock_irqrestore(&host->clk_lock, flags);
+        mutex_unlock(&host->clk_gate_mutex);
+}
+
+/*
+ * Internal work. Work to disable the clock at some later point.
+ */
+static void mmc_host_clk_gate_work(struct work_struct *work)
+{
+        struct mmc_host *host = container_of(work, struct mmc_host,
+                                              clk_gate_work);
+
+        mmc_host_clk_gate_delayed(host);
+}
+
+/**
+ *      mmc_host_clk_ungate - ungate hardware MCI clocks
+ *      @host: host to ungate.
+ *
+ *      Makes sure the host ios.clock is restored to a non-zero value
+ *      past this call. Increase clock reference count and ungate clock
+ *      if we're the first user.
+ */
+void mmc_host_clk_ungate(struct mmc_host *host)
+{
+        unsigned long flags;
+
+        mutex_lock(&host->clk_gate_mutex);
+        spin_lock_irqsave(&host->clk_lock, flags);
+        if (host->clk_gated) {
+                spin_unlock_irqrestore(&host->clk_lock, flags);
+                mmc_ungate_clock(host);
+                spin_lock_irqsave(&host->clk_lock, flags);
+                pr_debug("%s: ungated MCI clock\n", mmc_hostname(host));
+        }
+        host->clk_requests++;
+        spin_unlock_irqrestore(&host->clk_lock, flags);
+        mutex_unlock(&host->clk_gate_mutex);
+}
+
+/**
+ *      mmc_host_may_gate_card - check if this card may be gated
+ *      @card: card to check.
+ */
+static bool mmc_host_may_gate_card(struct mmc_card *card)
+{
+        /* If there is no card we may gate it */
+        if (!card)
+                return true;
+        /*
+         * Don't gate SDIO cards! These need to be clocked at all times
+         * since they may be independent systems generating interrupts
+         * and other events. The clock requests counter from the core will
+         * go down to zero since the core does not need it, but we will not
+         * gate the clock, because there is somebody out there that may still
+         * be using it.
+         */
+        if (mmc_card_sdio(card))
+                return false;
+
+        return true;
+}
+
+/**
+ *      mmc_host_clk_gate - gate off hardware MCI clocks
+ *      @host: host to gate.
+ *
+ *      Calls the host driver with ios.clock set to zero as often as possible
+ *      in order to gate off hardware MCI clocks. Decrease clock reference
+ *      count and schedule disabling of clock.
+ */
+void mmc_host_clk_gate(struct mmc_host *host)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&host->clk_lock, flags);
+        host->clk_requests--;
+        if (mmc_host_may_gate_card(host->card) &&
+            !host->clk_requests)
+                schedule_work(&host->clk_gate_work);
+        spin_unlock_irqrestore(&host->clk_lock, flags);
+}
+
+/**
+ *      mmc_host_clk_rate - get current clock frequency setting
+ *      @host: host to get the clock frequency for.
+ *
+ *      Returns current clock frequency regardless of gating.
+ */
+unsigned int mmc_host_clk_rate(struct mmc_host *host)
+{
+        unsigned long freq;
+        unsigned long flags;
+
+        spin_lock_irqsave(&host->clk_lock, flags);
+        if (host->clk_gated)
+                freq = host->clk_old;
+        else
+                freq = host->ios.clock;
+        spin_unlock_irqrestore(&host->clk_lock, flags);
+        return freq;
+}
+
+/**
+ *      mmc_host_clk_init - set up clock gating code
+ *      @host: host with potential clock to control
+ */
+static inline void mmc_host_clk_init(struct mmc_host *host)
+{
+        host->clk_requests = 0;
+        /* Hold MCI clock for 8 cycles by default */
+        host->clk_delay = 8;
+        host->clk_gated = false;
+        INIT_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
+        spin_lock_init(&host->clk_lock);
+        mutex_init(&host->clk_gate_mutex);
+}
+
+/**
+ *      mmc_host_clk_exit - shut down clock gating code
+ *      @host: host with potential clock to control
+ */
+static inline void mmc_host_clk_exit(struct mmc_host *host)
+{
+        /*
+         * Wait for any outstanding gate and then make sure we're
+         * ungated before exiting.
+         */
+        if (cancel_work_sync(&host->clk_gate_work))
+                mmc_host_clk_gate_delayed(host);
+        if (host->clk_gated)
+                mmc_host_clk_ungate(host);
+        /* There should be only one user now */
+        WARN_ON(host->clk_requests > 1);
+}
+
+#else
+
+static inline void mmc_host_clk_init(struct mmc_host *host)
+{
+}
+
+static inline void mmc_host_clk_exit(struct mmc_host *host)
+{
+}
+
+#endif
+
 /**
  *      mmc_alloc_host - initialise the per-host structure.
  *      @extra: sizeof private data structure
@@ -82,6 +283,8 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
         host->class_dev.class = &mmc_host_class;
         device_initialize(&host->class_dev);
 
+        mmc_host_clk_init(host);
+
         spin_lock_init(&host->lock);
         init_waitqueue_head(&host->wq);
         INIT_DELAYED_WORK(&host->detect, mmc_rescan);
@@ -163,6 +366,8 @@ void mmc_remove_host(struct mmc_host *host)
         device_del(&host->class_dev);
 
         led_trigger_unregister_simple(host->led);
+
+        mmc_host_clk_exit(host);
 }
 
 EXPORT_SYMBOL(mmc_remove_host);
@@ -183,4 +388,3 @@ void mmc_free_host(struct mmc_host *host)
 }
 
 EXPORT_SYMBOL(mmc_free_host);
-