*
* 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
#include <linux/suspend.h>
#include <linux/mmc/host.h>
+#include <linux/mmc/card.h>
#include "core.h"
#include "host.h"
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
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);
device_del(&host->class_dev);
led_trigger_unregister_simple(host->led);
+
+ mmc_host_clk_exit(host);
}
EXPORT_SYMBOL(mmc_remove_host);
}
EXPORT_SYMBOL(mmc_free_host);
-
projects / mv-sheeva.git / blobdiff