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Fri, 21 Jan 2011 11:34:51 -0800 From: Philip Rakity To: "linux-mmc@vger.kernel.org" CC: Mark Brown Date: Fri, 21 Jan 2011 11:34:51 -0800 Subject: [PATCH] ] mmc: add support for H/W clock gating of SD controller Thread-Topic: [PATCH] ] mmc: add support for H/W clock gating of SD controller Thread-Index: Acu5okV+aJTB+TzXTPqc3H/uXdra8w== Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US MIME-Version: 1.0 Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Fri, 21 Jan 2011 19:36:09 +0000 (UTC) diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 198f70b..281c7d9 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -683,10 +683,35 @@ void mmc_ungate_clock(struct mmc_host *host) } } +/* + * Let hardware automatically gate the clock when the card becomes idle + */ +void mmc_hwgate_clock(struct mmc_host *host) +{ + if (host->caps & MMC_CAP_HW_CLOCK_GATING) { + host->clk_gated = true; + mmc_set_ios(host); + } +} + +/* + * This ungates the clock by turning off h/w gating + */ +void mmc_hwungate_clock(struct mmc_host *host) +{ + if (host->caps & MMC_CAP_HW_CLOCK_GATING) { + host->clk_gated = false; + mmc_set_ios(host); + } +} + + void mmc_set_ungated(struct mmc_host *host) { unsigned long flags; + if (host->caps & MMC_CAP_HW_CLOCK_GATING) + return; /* * We've been given a new frequency while the clock is gated, * so make sure we regard this as ungating it. @@ -1487,6 +1512,7 @@ EXPORT_SYMBOL(mmc_set_blocklen); static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq) { + int ret; host->f_init = freq; #ifdef CONFIG_MMC_DEBUG @@ -1496,19 +1522,30 @@ static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq) mmc_power_up(host); sdio_reset(host); mmc_go_idle(host); + mmc_hwungate_clock(host); mmc_send_if_cond(host, host->ocr_avail); /* Order's important: probe SDIO, then SD, then MMC */ if (!mmc_attach_sdio(host)) - return 0; - if (!mmc_attach_sd(host)) - return 0; - if (!mmc_attach_mmc(host)) - return 0; + ret = 0; + else if (!mmc_attach_sd(host)) + ret = 0; + else if (!mmc_attach_mmc(host)) + ret = 0; + else + ret = -EIO; - mmc_power_off(host); - return -EIO; + if (ret == 0) { +#ifdef CONFIG_MMC_CLKGATE + if (mmc_host_may_gate_card(host->card)) + mmc_hwgate_clock(host); + else + mmc_hwungate_clock(host); +#endif + } else + mmc_power_off(host); + return ret; } void mmc_rescan(struct work_struct *work) diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h index ca1fdde..1972a38 100644 --- a/drivers/mmc/core/core.h +++ b/drivers/mmc/core/core.h @@ -35,6 +35,19 @@ void mmc_set_chip_select(struct mmc_host *host, int mode); void mmc_set_clock(struct mmc_host *host, unsigned int hz); void mmc_gate_clock(struct mmc_host *host); void mmc_ungate_clock(struct mmc_host *host); + +#ifdef CONFIG_MMC_CLKGATE +void mmc_hwgate_clock(struct mmc_host *host); +void mmc_hwungate_clock(struct mmc_host *host); +#else +static inline void mmc_hwgate_clock(struct mmc_host *host) +{ +} + +static inline void mmc_hwungate_clock(struct mmc_host *host) +{ +} +#endif void mmc_set_ungated(struct mmc_host *host); void mmc_set_bus_mode(struct mmc_host *host, unsigned int mode); void mmc_set_bus_width(struct mmc_host *host, unsigned int width); diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c index b3ac6c5..04a269d 100644 --- a/drivers/mmc/core/host.c +++ b/drivers/mmc/core/host.c @@ -130,6 +130,9 @@ void mmc_host_clk_ungate(struct mmc_host *host) { unsigned long flags; + if (host->caps & MMC_CAP_HW_CLOCK_GATING) + return; + mutex_lock(&host->clk_gate_mutex); spin_lock_irqsave(&host->clk_lock, flags); if (host->clk_gated) { @@ -147,7 +150,7 @@ void mmc_host_clk_ungate(struct mmc_host *host) * 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) +bool mmc_host_may_gate_card(struct mmc_card *card) { /* If there is no card we may gate it */ if (!card) @@ -178,6 +181,9 @@ void mmc_host_clk_gate(struct mmc_host *host) { unsigned long flags; + if (host->caps & MMC_CAP_HW_CLOCK_GATING) + return; + spin_lock_irqsave(&host->clk_lock, flags); host->clk_requests--; if (mmc_host_may_gate_card(host->card) && @@ -198,7 +204,10 @@ unsigned int mmc_host_clk_rate(struct mmc_host *host) unsigned long flags; spin_lock_irqsave(&host->clk_lock, flags); - if (host->clk_gated) + freq = host->ios.clock; + if (host->caps & MMC_CAP_HW_CLOCK_GATING) + freq = host->ios.clock; + else if (host->clk_gated) freq = host->clk_old; else freq = host->ios.clock; @@ -212,6 +221,9 @@ unsigned int mmc_host_clk_rate(struct mmc_host *host) */ static inline void mmc_host_clk_init(struct mmc_host *host) { + if (host->caps & MMC_CAP_HW_CLOCK_GATING) + return; + host->clk_requests = 0; /* Hold MCI clock for 8 cycles by default */ host->clk_delay = 8; @@ -227,6 +239,9 @@ static inline void mmc_host_clk_init(struct mmc_host *host) */ static inline void mmc_host_clk_exit(struct mmc_host *host) { + if (host->caps & MMC_CAP_HW_CLOCK_GATING) + return; + /* * Wait for any outstanding gate and then make sure we're * ungated before exiting. diff --git a/drivers/mmc/core/host.h b/drivers/mmc/core/host.h index de199f9..db9d407 100644 --- a/drivers/mmc/core/host.h +++ b/drivers/mmc/core/host.h @@ -19,6 +19,7 @@ void mmc_unregister_host_class(void); void mmc_host_clk_ungate(struct mmc_host *host); void mmc_host_clk_gate(struct mmc_host *host); unsigned int mmc_host_clk_rate(struct mmc_host *host); +bool mmc_host_may_gate_card(struct mmc_card *card); #else static inline void mmc_host_clk_ungate(struct mmc_host *host) diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 359924c..f51b1b2 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -174,6 +174,7 @@ struct mmc_host { /* DDR mode at 1.2V */ #define MMC_CAP_POWER_OFF_CARD (1 << 13) /* Can power off after boot */ #define MMC_CAP_BUS_WIDTH_TEST (1 << 14) /* CMD14/CMD19 bus width ok */ +#define MMC_CAP_HW_CLOCK_GATING (1 << 15) /* h/w supports clock gating */ mmc_pm_flag_t pm_caps; /* supported pm features */