diff options
Diffstat (limited to 'drivers/mmc/core/host.c')
| -rw-r--r-- | drivers/mmc/core/host.c | 206 |
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); - |