mmc: mediatek: add support for SDIO eint wakup IRQ

Add support for eint IRQ when MSDC is used as an SDIO host. This
feature requires SDIO device support async IRQ function. With this
feature, SDIO host can be awakened by SDIO card in suspend state,
without additional pin.

MSDC driver will time-share the SDIO DAT1 pin. During suspend, MSDC
turn off clock and switch SDIO DAT1 pin to GPIO mode. And during
resume, switch GPIO function back to DAT1 mode then turn on clock.

Some device tree property should be added or modified in MSDC node
to support SDIO eint IRQ. Pinctrls "state_eint" is mandatory. Since
this feature depends on asynchronous interrupts, "wakeup-source",
"keep-power-in-suspend" and "cap-sdio-irq" flags are necessary, and
the interrupts list should be extended(the interrupt named with
sdio_wakeup):
        &mmcX {
		...
		interrupt-names = "msdc", "sdio_wakeup";
		interrupts-extended = <...>,
                              	      <&pio xxx IRQ_TYPE_LEVEL_LOW>;
                ...
                pinctrl-names = "default", "state_uhs", "state_eint";
                ...
                pinctrl-2 = <&mmc2_pins_eint>;
                ...
                cap-sdio-irq;
		keep-power-in-suspend;
		wakeup-source;
                ...
        };

Co-developed-by: Yong Mao <[email protected]>
Signed-off-by: Yong Mao <[email protected]>
Reviewed-by: Chaotian Jing <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>
Signed-off-by: Axe Yang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ulf Hansson <[email protected]>

Author: Axe Yang

drivers/mmc/host/mtk-sd.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2014-2015 MediaTek Inc.
+ * Copyright (c) 2014-2015, 2022 MediaTek Inc.
  * Author: Chaotian.Jing <[email protected]>
  */
 
@@ -20,6 +20,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
+#include <linux/pm_wakeirq.h>
 #include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
@@ -440,8 +441,10 @@ struct msdc_host {
 	struct pinctrl *pinctrl;
 	struct pinctrl_state *pins_default;
 	struct pinctrl_state *pins_uhs;
+	struct pinctrl_state *pins_eint;
 	struct delayed_work req_timeout;
 	int irq;		/* host interrupt */
+	int eint_irq;		/* interrupt from sdio device for waking up system */
 	struct reset_control *reset;
 
 	struct clk *src_clk;	/* msdc source clock */
@@ -1521,17 +1524,46 @@ static void __msdc_enable_sdio_irq(struct msdc_host *host, int enb)
 
 static void msdc_enable_sdio_irq(struct mmc_host *mmc, int enb)
 {
-	unsigned long flags;
 	struct msdc_host *host = mmc_priv(mmc);
+	unsigned long flags;
+	int ret;
 
 	spin_lock_irqsave(&host->lock, flags);
 	__msdc_enable_sdio_irq(host, enb);
 	spin_unlock_irqrestore(&host->lock, flags);
 
-	if (enb)
-		pm_runtime_get_noresume(host->dev);
-	else
-		pm_runtime_put_noidle(host->dev);
+	if (mmc_card_enable_async_irq(mmc->card) && host->pins_eint) {
+		if (enb) {
+			/*
+			 * In dev_pm_set_dedicated_wake_irq_reverse(), eint pin will be set to
+			 * GPIO mode. We need to restore it to SDIO DAT1 mode after that.
+			 * Since the current pinstate is pins_uhs, to ensure pinctrl select take
+			 * affect successfully, we change the pinstate to pins_eint firstly.
+			 */
+			pinctrl_select_state(host->pinctrl, host->pins_eint);
+			ret = dev_pm_set_dedicated_wake_irq_reverse(host->dev, host->eint_irq);
+
+			if (ret) {
+				dev_err(host->dev, "Failed to register SDIO wakeup irq!\n");
+				host->pins_eint = NULL;
+				pm_runtime_get_noresume(host->dev);
+			} else {
+				dev_dbg(host->dev, "SDIO eint irq: %d!\n", host->eint_irq);
+			}
+
+			pinctrl_select_state(host->pinctrl, host->pins_uhs);
+		} else {
+			dev_pm_clear_wake_irq(host->dev);
+		}
+	} else {
+		if (enb) {
+			/* Ensure host->pins_eint is NULL */
+			host->pins_eint = NULL;
+			pm_runtime_get_noresume(host->dev);
+		} else {
+			pm_runtime_put_noidle(host->dev);
+		}
+	}
 }
 
 static irqreturn_t msdc_cmdq_irq(struct msdc_host *host, u32 intsts)
@@ -2635,6 +2667,20 @@ static int msdc_drv_probe(struct platform_device *pdev)
 		goto host_free;
 	}
 
+	/* Support for SDIO eint irq ? */
+	if ((mmc->pm_caps & MMC_PM_WAKE_SDIO_IRQ) && (mmc->pm_caps & MMC_PM_KEEP_POWER)) {
+		host->eint_irq = platform_get_irq_byname(pdev, "sdio_wakeup");
+		if (host->eint_irq > 0) {
+			host->pins_eint = pinctrl_lookup_state(host->pinctrl, "state_eint");
+			if (IS_ERR(host->pins_eint)) {
+				dev_err(&pdev->dev, "Cannot find pinctrl eint!\n");
+				host->pins_eint = NULL;
+			} else {
+				device_init_wakeup(&pdev->dev, true);
+			}
+		}
+	}
+
 	msdc_of_property_parse(pdev, host);
 
 	host->dev = &pdev->dev;
@@ -2849,6 +2895,15 @@ static int __maybe_unused msdc_runtime_suspend(struct device *dev)
 	struct msdc_host *host = mmc_priv(mmc);
 
 	msdc_save_reg(host);
+
+	if (sdio_irq_claimed(mmc)) {
+		if (host->pins_eint) {
+			disable_irq(host->irq);
+			pinctrl_select_state(host->pinctrl, host->pins_eint);
+		}
+
+		__msdc_enable_sdio_irq(host, 0);
+	}
 	msdc_gate_clock(host);
 	return 0;
 }
@@ -2864,12 +2919,18 @@ static int __maybe_unused msdc_runtime_resume(struct device *dev)
 		return ret;
 
 	msdc_restore_reg(host);
+
+	if (sdio_irq_claimed(mmc) && host->pins_eint) {
+		pinctrl_select_state(host->pinctrl, host->pins_uhs);
+		enable_irq(host->irq);
+	}
 	return 0;
 }
 
 static int __maybe_unused msdc_suspend(struct device *dev)
 {
 	struct mmc_host *mmc = dev_get_drvdata(dev);
+	struct msdc_host *host = mmc_priv(mmc);
 	int ret;
 
 	if (mmc->caps2 & MMC_CAP2_CQE) {
@@ -2878,11 +2939,24 @@ static int __maybe_unused msdc_suspend(struct device *dev)
 			return ret;
 	}
 
+	/*
+	 * Bump up runtime PM usage counter otherwise dev->power.needs_force_resume will
+	 * not be marked as 1, pm_runtime_force_resume() will go out directly.
+	 */
+	if (sdio_irq_claimed(mmc) && host->pins_eint)
+		pm_runtime_get_noresume(dev);
+
 	return pm_runtime_force_suspend(dev);
 }
 
 static int __maybe_unused msdc_resume(struct device *dev)
 {
+	struct mmc_host *mmc = dev_get_drvdata(dev);
+	struct msdc_host *host = mmc_priv(mmc);
+
+	if (sdio_irq_claimed(mmc) && host->pins_eint)
+		pm_runtime_put_noidle(dev);
+
 	return pm_runtime_force_resume(dev);
 }