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MMC: OMAP: Lazy clock shutdown 

MMCA spec says the mmc clock should be kept running for at least
8 cycles after the last RW request. Ensure this with lazy clock
disable after a request, or with an explicit delay before
switching a slot.

Signed-off-by: Jarkko Lavinen <jarkko.lavinen@nokia.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
This commit is contained in:
Jarkko Lavinen 2008-03-26 16:09:52 -04:00 committed by Pierre Ossman
parent 0fb4723d40
commit 0807a9b573
1 changed files with 75 additions and 14 deletions
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89
drivers/mmc/host/omap.c
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@ -161,9 +161,38 @@ struct mmc_omap_host {
wait_queue_head_t slot_wq;
int nr_slots;
struct timer_list clk_timer;
spinlock_t clk_lock; /* for changing enabled state */
unsigned int fclk_enabled:1;
struct omap_mmc_platform_data *pdata;
};
void mmc_omap_fclk_offdelay(struct mmc_omap_slot *slot)
{
unsigned long tick_ns;
if (slot != NULL && slot->host->fclk_enabled && slot->fclk_freq > 0) {
tick_ns = (1000000000 + slot->fclk_freq - 1) / slot->fclk_freq;
ndelay(8 * tick_ns);
}
}
void mmc_omap_fclk_enable(struct mmc_omap_host *host, unsigned int enable)
{
unsigned long flags;
spin_lock_irqsave(&host->clk_lock, flags);
if (host->fclk_enabled != enable) {
host->fclk_enabled = enable;
if (enable)
clk_enable(host->fclk);
else
clk_disable(host->fclk);
}
spin_unlock_irqrestore(&host->clk_lock, flags);
}
static void mmc_omap_select_slot(struct mmc_omap_slot *slot, int claimed)
{
struct mmc_omap_host *host = slot->host;
@ -180,32 +209,49 @@ static void mmc_omap_select_slot(struct mmc_omap_slot *slot, int claimed)
host->mmc = slot->mmc;
spin_unlock_irqrestore(&host->slot_lock, flags);
no_claim:
clk_enable(host->fclk);
del_timer(&host->clk_timer);
if (host->current_slot != slot || !claimed)
mmc_omap_fclk_offdelay(host->current_slot);
if (host->current_slot != slot) {
OMAP_MMC_WRITE(host, CON, slot->saved_con & 0xFC00);
if (host->pdata->switch_slot != NULL)
host->pdata->switch_slot(mmc_dev(slot->mmc), slot->id);
host->current_slot = slot;
}
/* Doing the dummy read here seems to work around some bug
* at least in OMAP24xx silicon where the command would not
* start after writing the CMD register. Sigh. */
OMAP_MMC_READ(host, CON);
if (claimed) {
mmc_omap_fclk_enable(host, 1);
OMAP_MMC_WRITE(host, CON, slot->saved_con);
/* Doing the dummy read here seems to work around some bug
* at least in OMAP24xx silicon where the command would not
* start after writing the CMD register. Sigh. */
OMAP_MMC_READ(host, CON);
OMAP_MMC_WRITE(host, CON, slot->saved_con);
} else
mmc_omap_fclk_enable(host, 0);
}
static void mmc_omap_start_request(struct mmc_omap_host *host,
struct mmc_request *req);
static void mmc_omap_release_slot(struct mmc_omap_slot *slot)
static void mmc_omap_release_slot(struct mmc_omap_slot *slot, int clk_enabled)
{
struct mmc_omap_host *host = slot->host;
unsigned long flags;
int i;
BUG_ON(slot == NULL || host->mmc == NULL);
clk_disable(host->fclk);
if (clk_enabled)
/* Keeps clock running for at least 8 cycles on valid freq */
mod_timer(&host->clk_timer, jiffies + HZ/10);
else {
del_timer(&host->clk_timer);
mmc_omap_fclk_offdelay(slot);
mmc_omap_fclk_enable(host, 0);
}
spin_lock_irqsave(&host->slot_lock, flags);
/* Check for any pending requests */
@ -373,7 +419,7 @@ mmc_omap_xfer_done(struct mmc_omap_host *host, struct mmc_data *data)
host->mrq = NULL;
mmc = host->mmc;
mmc_omap_release_slot(host->current_slot);
mmc_omap_release_slot(host->current_slot, 1);
mmc_request_done(mmc, data->mrq);
return;
}
@ -507,7 +553,7 @@ mmc_omap_cmd_done(struct mmc_omap_host *host, struct mmc_command *cmd)
mmc_omap_abort_xfer(host, host->data);
host->mrq = NULL;
mmc = host->mmc;
mmc_omap_release_slot(host->current_slot);
mmc_omap_release_slot(host->current_slot, 1);
mmc_request_done(mmc, cmd->mrq);
}
}
@ -538,7 +584,7 @@ static void mmc_omap_abort_command(struct work_struct *work)
host->mrq = NULL;
mmc = host->mmc;
mmc_omap_release_slot(host->current_slot);
mmc_omap_release_slot(host->current_slot, 1);
mmc_request_done(mmc, cmd->mrq);
} else
mmc_omap_cmd_done(host, host->cmd);
@ -576,6 +622,14 @@ mmc_omap_sg_to_buf(struct mmc_omap_host *host)
host->buffer_bytes_left = host->total_bytes_left;
}
static void
mmc_omap_clk_timer(unsigned long data)
{
struct mmc_omap_host *host = (struct mmc_omap_host *) data;
mmc_omap_fclk_enable(host, 0);
}
/* PIO only */
static void
mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
@ -1149,14 +1203,16 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
struct mmc_omap_slot *slot = mmc_priv(mmc);
struct mmc_omap_host *host = slot->host;
int i, dsor;
dsor = mmc_omap_calc_divisor(mmc, ios);
int clk_enabled;
mmc_omap_select_slot(slot, 0);
dsor = mmc_omap_calc_divisor(mmc, ios);
if (ios->vdd != slot->vdd)
slot->vdd = ios->vdd;
clk_enabled = 0;
switch (ios->power_mode) {
case MMC_POWER_OFF:
mmc_omap_set_power(slot, 0, ios->vdd);
@ -1166,6 +1222,8 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
mmc_omap_set_power(slot, 1, ios->vdd);
goto exit;
case MMC_POWER_ON:
mmc_omap_fclk_enable(host, 1);
clk_enabled = 1;
dsor |= 1 << 11;
break;
}
@ -1194,7 +1252,7 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
}
exit:
mmc_omap_release_slot(slot);
mmc_omap_release_slot(slot, clk_enabled);
}
static const struct mmc_host_ops mmc_omap_ops = {
@ -1335,6 +1393,9 @@ static int __init mmc_omap_probe(struct platform_device *pdev)
setup_timer(&host->cmd_abort_timer, mmc_omap_cmd_timer,
(unsigned long) host);
spin_lock_init(&host->clk_lock);
setup_timer(&host->clk_timer, mmc_omap_clk_timer, (unsigned long) host);
spin_lock_init(&host->dma_lock);
setup_timer(&host->dma_timer, mmc_omap_dma_timer, (unsigned long) host);
spin_lock_init(&host->slot_lock);