mmc: sdhci-msm: Add sdhci msm register write APIs which wait for pwr irq

Register writes which change voltage of IO lines or turn the IO bus
on/off require controller to be ready before progressing further. When
the controller is ready, it will generate a power irq which needs to be
handled. The thread which initiated the register write should wait for
power irq to complete. This will be done through the new sdhc msm write
APIs which will check whether the particular write can trigger a power
irq and wait for it with a timeout if it is expected.
The SDHC core power control IRQ gets triggered when -
* There is a state change in power control bit (bit 0)
  of SDHCI_POWER_CONTROL register.
* There is a state change in 1.8V enable bit (bit 3) of
  SDHCI_HOST_CONTROL2 register.
* Bit 1 of SDHCI_SOFTWARE_RESET is set.

Also add support APIs which are used by sdhc msm write APIs to check
if power irq is expected to be generated and wait for the power irq
to come and complete if the irq is expected.

This patch requires CONFIG_MMC_SDHCI_IO_ACCESSORS to be enabled.
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-msm.c

@@ -123,6 +123,10 @@
 #define CMUX_SHIFT_PHASE_MASK	(7 << CMUX_SHIFT_PHASE_SHIFT)
 
 #define MSM_MMC_AUTOSUSPEND_DELAY_MS	50
+
+/* Timeout value to avoid infinite waiting for pwr_irq */
+#define MSM_PWR_IRQ_TIMEOUT_MS 5000
+
 struct sdhci_msm_host {
 	struct platform_device *pdev;
 	void __iomem *core_mem;	/* MSM SDCC mapped address */
@@ -137,6 +141,10 @@ struct sdhci_msm_host {
 	bool calibration_done;
 	u8 saved_tuning_phase;
 	bool use_cdclp533;
+	u32 curr_pwr_state;
+	u32 curr_io_level;
+	wait_queue_head_t pwr_irq_wait;
+	bool pwr_irq_flag;
 };
 
 static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host,
@@ -995,6 +1003,73 @@ static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
 		sdhci_msm_hs400(host, &mmc->ios);
 }
 
+static inline void sdhci_msm_init_pwr_irq_wait(struct sdhci_msm_host *msm_host)
+{
+	init_waitqueue_head(&msm_host->pwr_irq_wait);
+}
+
+static inline void sdhci_msm_complete_pwr_irq_wait(
+		struct sdhci_msm_host *msm_host)
+{
+	wake_up(&msm_host->pwr_irq_wait);
+}
+
+/*
+ * sdhci_msm_check_power_status API should be called when registers writes
+ * which can toggle sdhci IO bus ON/OFF or change IO lines HIGH/LOW happens.
+ * To what state the register writes will change the IO lines should be passed
+ * as the argument req_type. This API will check whether the IO line's state
+ * is already the expected state and will wait for power irq only if
+ * power irq is expected to be trigerred based on the current IO line state
+ * and expected IO line state.
+ */
+static void sdhci_msm_check_power_status(struct sdhci_host *host, u32 req_type)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
+	bool done = false;
+
+	pr_debug("%s: %s: request %d curr_pwr_state %x curr_io_level %x\n",
+			mmc_hostname(host->mmc), __func__, req_type,
+			msm_host->curr_pwr_state, msm_host->curr_io_level);
+
+	/*
+	 * The IRQ for request type IO High/LOW will be generated when -
+	 * there is a state change in 1.8V enable bit (bit 3) of
+	 * SDHCI_HOST_CONTROL2 register. The reset state of that bit is 0
+	 * which indicates 3.3V IO voltage. So, when MMC core layer tries
+	 * to set it to 3.3V before card detection happens, the
+	 * IRQ doesn't get triggered as there is no state change in this bit.
+	 * The driver already handles this case by changing the IO voltage
+	 * level to high as part of controller power up sequence. Hence, check
+	 * for host->pwr to handle a case where IO voltage high request is
+	 * issued even before controller power up.
+	 */
+	if ((req_type & REQ_IO_HIGH) && !host->pwr) {
+		pr_debug("%s: do not wait for power IRQ that never comes, req_type: %d\n",
+				mmc_hostname(host->mmc), req_type);
+		return;
+	}
+	if ((req_type & msm_host->curr_pwr_state) ||
+			(req_type & msm_host->curr_io_level))
+		done = true;
+	/*
+	 * This is needed here to handle cases where register writes will
+	 * not change the current bus state or io level of the controller.
+	 * In this case, no power irq will be triggerred and we should
+	 * not wait.
+	 */
+	if (!done) {
+		if (!wait_event_timeout(msm_host->pwr_irq_wait,
+				msm_host->pwr_irq_flag,
+				msecs_to_jiffies(MSM_PWR_IRQ_TIMEOUT_MS)))
+			__WARN_printf("%s: pwr_irq for req: (%d) timed out\n",
+					mmc_hostname(host->mmc), req_type);
+	}
+	pr_debug("%s: %s: request %d done\n", mmc_hostname(host->mmc),
+			__func__, req_type);
+}
+
 static void sdhci_msm_dump_pwr_ctrl_regs(struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -1013,6 +1088,8 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
 	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
 	u32 irq_status, irq_ack = 0;
 	int retry = 10;
+	int pwr_state = 0, io_level = 0;
+
 
 	irq_status = readl_relaxed(msm_host->core_mem + CORE_PWRCTL_STATUS);
 	irq_status &= INT_MASK;
@@ -1041,10 +1118,26 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
 		udelay(10);
 	}
 
-	if (irq_status & (CORE_PWRCTL_BUS_ON | CORE_PWRCTL_BUS_OFF))
+	/* Handle BUS ON/OFF*/
+	if (irq_status & CORE_PWRCTL_BUS_ON) {
+		pwr_state = REQ_BUS_ON;
+		io_level = REQ_IO_HIGH;
+		irq_ack |= CORE_PWRCTL_BUS_SUCCESS;
+	}
+	if (irq_status & CORE_PWRCTL_BUS_OFF) {
+		pwr_state = REQ_BUS_OFF;
+		io_level = REQ_IO_LOW;
 		irq_ack |= CORE_PWRCTL_BUS_SUCCESS;
-	if (irq_status & (CORE_PWRCTL_IO_LOW | CORE_PWRCTL_IO_HIGH))
+	}
+	/* Handle IO LOW/HIGH */
+	if (irq_status & CORE_PWRCTL_IO_LOW) {
+		io_level = REQ_IO_LOW;
 		irq_ack |= CORE_PWRCTL_IO_SUCCESS;
+	}
+	if (irq_status & CORE_PWRCTL_IO_HIGH) {
+		io_level = REQ_IO_HIGH;
+		irq_ack |= CORE_PWRCTL_IO_SUCCESS;
+	}
 
 	/*
 	 * The driver has to acknowledge the interrupt, switch voltages and
@@ -1053,6 +1146,11 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
 	 */
 	writel_relaxed(irq_ack, msm_host->core_mem + CORE_PWRCTL_CTL);
 
+	if (pwr_state)
+		msm_host->curr_pwr_state = pwr_state;
+	if (io_level)
+		msm_host->curr_io_level = io_level;
+
 	pr_debug("%s: %s: Handled IRQ(%d), irq_status=0x%x, ack=0x%x\n",
 		mmc_hostname(msm_host->mmc), __func__, irq, irq_status,
 		irq_ack);
@@ -1061,8 +1159,13 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
 static irqreturn_t sdhci_msm_pwr_irq(int irq, void *data)
 {
 	struct sdhci_host *host = (struct sdhci_host *)data;
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
 
 	sdhci_msm_handle_pwr_irq(host, irq);
+	msm_host->pwr_irq_flag = 1;
+	sdhci_msm_complete_pwr_irq_wait(msm_host);
+
 
 	return IRQ_HANDLED;
 }
@@ -1132,6 +1235,69 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
 	__sdhci_msm_set_clock(host, clock);
 }
 
+/*
+ * Platform specific register write functions. This is so that, if any
+ * register write needs to be followed up by platform specific actions,
+ * they can be added here. These functions can go to sleep when writes
+ * to certain registers are done.
+ * These functions are relying on sdhci_set_ios not using spinlock.
+ */
+static int __sdhci_msm_check_write(struct sdhci_host *host, u16 val, int reg)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
+	u32 req_type = 0;
+
+	switch (reg) {
+	case SDHCI_HOST_CONTROL2:
+		req_type = (val & SDHCI_CTRL_VDD_180) ? REQ_IO_LOW :
+			REQ_IO_HIGH;
+		break;
+	case SDHCI_SOFTWARE_RESET:
+		if (host->pwr && (val & SDHCI_RESET_ALL))
+			req_type = REQ_BUS_OFF;
+		break;
+	case SDHCI_POWER_CONTROL:
+		req_type = !val ? REQ_BUS_OFF : REQ_BUS_ON;
+		break;
+	}
+
+	if (req_type) {
+		msm_host->pwr_irq_flag = 0;
+		/*
+		 * Since this register write may trigger a power irq, ensure
+		 * all previous register writes are complete by this point.
+		 */
+		mb();
+	}
+	return req_type;
+}
+
+/* This function may sleep*/
+static void sdhci_msm_writew(struct sdhci_host *host, u16 val, int reg)
+{
+	u32 req_type = 0;
+
+	req_type = __sdhci_msm_check_write(host, val, reg);
+	writew_relaxed(val, host->ioaddr + reg);
+
+	if (req_type)
+		sdhci_msm_check_power_status(host, req_type);
+}
+
+/* This function may sleep*/
+static void sdhci_msm_writeb(struct sdhci_host *host, u8 val, int reg)
+{
+	u32 req_type = 0;
+
+	req_type = __sdhci_msm_check_write(host, val, reg);
+
+	writeb_relaxed(val, host->ioaddr + reg);
+
+	if (req_type)
+		sdhci_msm_check_power_status(host, req_type);
+}
+
 static const struct of_device_id sdhci_msm_dt_match[] = {
 	{ .compatible = "qcom,sdhci-msm-v4" },
 	{},
@@ -1146,6 +1312,8 @@ static const struct sdhci_ops sdhci_msm_ops = {
 	.get_max_clock = sdhci_msm_get_max_clock,
 	.set_bus_width = sdhci_set_bus_width,
 	.set_uhs_signaling = sdhci_msm_set_uhs_signaling,
+	.write_w = sdhci_msm_writew,
+	.write_b = sdhci_msm_writeb,
 };
 
 static const struct sdhci_pltfm_data sdhci_msm_pdata = {
@@ -1324,6 +1492,7 @@ static int sdhci_msm_probe(struct platform_device *pdev)
 		goto clk_disable;
 	}
 
+	sdhci_msm_init_pwr_irq_wait(msm_host);
 	/* Enable pwr irq interrupts */
 	writel_relaxed(INT_MASK, msm_host->core_mem + CORE_PWRCTL_MASK);