mmc: core: Remove MMC_CLKGATE

MMC_CLKGATE was once invented to save power by gating the bus clock at
request inactivity. At that time it served its purpose. The modern way to
deal with power saving for these scenarios, is by using runtime PM.

Nowadays, several host drivers have deployed runtime PM, but for those
that haven't and which still cares power saving at request inactivity,
it's certainly time to deploy runtime PM as it has been around for several
years now.

To simplify code to mmc core and thus decrease maintenance efforts, this
patch removes all code related to MMC_CLKGATE.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 0 insertions, 245 deletions

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 5466f25f0281..970e6906930b 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -61,246 +61,6 @@ void mmc_unregister_host_class(void)
 	class_unregister(&mmc_host_class);
 }
 
-#ifdef CONFIG_MMC_CLKGATE
-static ssize_t clkgate_delay_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct mmc_host *host = cls_dev_to_mmc_host(dev);
-	return snprintf(buf, PAGE_SIZE, "%lu\n", host->clkgate_delay);
-}
-
-static ssize_t clkgate_delay_store(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t count)
-{
-	struct mmc_host *host = cls_dev_to_mmc_host(dev);
-	unsigned long flags, value;
-
-	if (kstrtoul(buf, 0, &value))
-		return -EINVAL;
-
-	spin_lock_irqsave(&host->clk_lock, flags);
-	host->clkgate_delay = value;
-	spin_unlock_irqrestore(&host->clk_lock, flags);
-	return count;
-}
-
-/*
- * 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.work);
-
-	mmc_host_clk_gate_delayed(host);
-}
-
-/**
- *	mmc_host_clk_hold - 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_hold(struct mmc_host *host)
-{
-	unsigned long flags;
-
-	/* cancel any clock gating work scheduled by mmc_host_clk_release() */
-	cancel_delayed_work_sync(&host->clk_gate_work);
-	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.
-	 */
-	return !(card->quirks & MMC_QUIRK_BROKEN_CLK_GATING);
-}
-
-/**
- *	mmc_host_clk_release - 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_release(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_delayed_work(&host->clk_gate_work,
-				      msecs_to_jiffies(host->clkgate_delay));
-	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;
-	/*
-	 * Default clock gating delay is 0ms to avoid wasting power.
-	 * This value can be tuned by writing into sysfs entry.
-	 */
-	host->clkgate_delay = 0;
-	host->clk_gated = false;
-	INIT_DELAYED_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_delayed_work_sync(&host->clk_gate_work))
-		mmc_host_clk_gate_delayed(host);
-	if (host->clk_gated)
-		mmc_host_clk_hold(host);
-	/* There should be only one user now */
-	WARN_ON(host->clk_requests > 1);
-}
-
-static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
-{
-	host->clkgate_delay_attr.show = clkgate_delay_show;
-	host->clkgate_delay_attr.store = clkgate_delay_store;
-	sysfs_attr_init(&host->clkgate_delay_attr.attr);
-	host->clkgate_delay_attr.attr.name = "clkgate_delay";
-	host->clkgate_delay_attr.attr.mode = S_IRUGO | S_IWUSR;
-	if (device_create_file(&host->class_dev, &host->clkgate_delay_attr))
-		pr_err("%s: Failed to create clkgate_delay sysfs entry\n",
-				mmc_hostname(host));
-}
-#else
-
-static inline void mmc_host_clk_init(struct mmc_host *host)
-{
-}
-
-static inline void mmc_host_clk_exit(struct mmc_host *host)
-{
-}
-
-static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
-{
-}
-
-#endif
-
 void mmc_retune_enable(struct mmc_host *host)
 {
 	host->can_retune = 1;
@@ -583,8 +343,6 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 		return NULL;
 	}
 
-	mmc_host_clk_init(host);
-
 	spin_lock_init(&host->lock);
 	init_waitqueue_head(&host->wq);
 	INIT_DELAYED_WORK(&host->detect, mmc_rescan);
@@ -633,7 +391,6 @@ int mmc_add_host(struct mmc_host *host)
 #ifdef CONFIG_DEBUG_FS
 	mmc_add_host_debugfs(host);
 #endif
-	mmc_host_clk_sysfs_init(host);
 
 	mmc_start_host(host);
 	register_pm_notifier(&host->pm_notify);
@@ -663,8 +420,6 @@ 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);