[PATCH] mmc: sdhci-of-at91: allow the use of controller card detect as wake up

Ludovic Desroches
2016-03-25T16:05:03Z

At the moment, there are only two ways to wake up from runtime suspend state:
- using a gpio for the card detection which is not a good solution since
you still need the card detect pin of the controller.
- using polling which is also not a good solution since it will
resume/suspend the controller between each attempt.

The sdhci layer makes the assumption that all the clocks are disabled
when suspending the controller. For that reason, irqs are rejected if
runtime_suspended is true.

This patch duplicates the sdhci_runtime_suspend_host() but doesn't set
runtime_suspended and doesn't disable the interface clock if there is a
removable device and no gpio for card detection.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
---
drivers/mmc/host/sdhci-of-at91.c | 71 +++++++++++++++++++++++++---------------
1 file changed, 45 insertions(+), 26 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
index 2703aa9..6683f2d 100644
--- a/drivers/mmc/host/sdhci-of-at91.c
+++ b/drivers/mmc/host/sdhci-of-at91.c
@@ -35,6 +35,7 @@ struct sdhci_at91_priv {
struct clk *hclock;
struct clk *gck;
struct clk *mainck;
+ bool disable_interface_clk;
};

static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
@@ -55,20 +56,47 @@ static const struct of_device_id sdhci_at91_dt_match[] = {
};

#ifdef CONFIG_PM
+/*
+ * This function is the very same as sdhci_runtime_suspend_host but if the
+ * device is removable and we only have the controller card detect signal then
+ * we won't disable all the clocks. The interface clock will be needed to get
+ * card event interrupt.
+ * When calling sdhci_runtime_suspend_host(), the sdhci layer makes the
+ * assumption that all the clocks of the controller are disabled. If
+ * runtime_suspended is set, irqs will be rejected. That's why it won't be set
+ * if we want to wake up on card event.
+ */
static int sdhci_at91_runtime_suspend(struct device *dev)
{
struct sdhci_host *host = dev_get_drvdata(dev);
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
- int ret;
+ unsigned long flags;
+
+ mmc_retune_timer_stop(host->mmc);
+ mmc_retune_needed(host->mmc);
+
+ spin_lock_irqsave(&host->lock, flags);
+ host->ier &= SDHCI_INT_CARD_INT;
+ if (!priv->disable_interface_clk)
+ host->ier |= SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE;
+ sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
+ sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
+ spin_unlock_irqrestore(&host->lock, flags);

- ret = sdhci_runtime_suspend_host(host);
+ synchronize_hardirq(host->irq);
+
+ if (priv->disable_interface_clk) {
+ spin_lock_irqsave(&host->lock, flags);
+ host->runtime_suspended = true;
+ spin_unlock_irqrestore(&host->lock, flags);
+ clk_disable_unprepare(priv->hclock);
+ };

clk_disable_unprepare(priv->gck);
- clk_disable_unprepare(priv->hclock);
clk_disable_unprepare(priv->mainck);

- return ret;
+ return 0;
}

static int sdhci_at91_runtime_resume(struct device *dev)
@@ -84,18 +112,20 @@ static int sdhci_at91_runtime_resume(struct device *dev)
return ret;
}

- ret = clk_prepare_enable(priv->hclock);
- if (ret) {
- dev_err(dev, "can't enable hclock\n");
- return ret;
- }
-
ret = clk_prepare_enable(priv->gck);
if (ret) {
dev_err(dev, "can't enable gck\n");
return ret;
}

+ if (priv->disable_interface_clk) {
+ ret = clk_prepare_enable(priv->hclock);
+ if (ret) {
+ dev_err(dev, "can't enable hclock\n");
+ return ret;
+ }
+ }
+
return sdhci_runtime_resume_host(host);
}
#endif /* CONFIG_PM */
@@ -206,23 +236,12 @@ static int sdhci_at91_probe(struct platform_device *pdev)
goto pm_runtime_disable;

/*
- * When calling sdhci_runtime_suspend_host(), the sdhci layer makes
- * the assumption that all the clocks of the controller are disabled.
- * It means we can't get irq from it when it is runtime suspended.
- * For that reason, it is not planned to wake-up on a card detect irq
- * from the controller.
- * If we want to use runtime PM and to be able to wake-up on card
- * insertion, we have to use a GPIO for the card detection or we can
- * use polling. Be aware that using polling will resume/suspend the
- * controller between each attempt.
- * Disable SDHCI_QUIRK_BROKEN_CARD_DETECTION to be sure nobody tries
- * to enable polling via device tree with broken-cd property.
+ * If the device is non removable or if there is a gpio for the card
+ * detection, all the clocks can be disabled in runtime suspend state.
*/
- if (!(host->mmc->caps & MMC_CAP_NONREMOVABLE) &&
- IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc))) {
- host->mmc->caps |= MMC_CAP_NEEDS_POLL;
- host->quirks &= ~SDHCI_QUIRK_BROKEN_CARD_DETECTION;
- }
+ priv->disable_interface_clk = (host->mmc->caps & MMC_CAP_NONREMOVABLE)
+ || !IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc));
+

pm_runtime_put_autosuspend(&pdev->dev);

--
2.5.0