mmc: sdhci-pxav2: add SDIO card IRQ workaround for PXA168 V1 controller

The PXA168 has a documented silicon bug that causes SDIO card IRQs to be
missed. Implement the first half of the suggested workaround, which
involves resetting the data port logic and issuing a dummy CMD0 to
restart the clock.
Signed-off-by: Doug Brown <doug@schmorgal.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20230116194401.20372-7-doug@schmorgal.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-pxav2.c

@@ -20,6 +20,8 @@
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/mmc/sdio.h>
+#include <linux/mmc/mmc.h>
 
 #include "sdhci.h"
 #include "sdhci-pltfm.h"
@@ -41,6 +43,10 @@
 #define MMC_CARD		0x1000
 #define MMC_WIDTH		0x0100
 
+struct sdhci_pxav2_host {
+	struct mmc_request *sdio_mrq;
+};
+
 static void pxav2_reset(struct sdhci_host *host, u8 mask)
 {
 	struct platform_device *pdev = to_platform_device(mmc_dev(host->mmc));
@@ -89,6 +95,52 @@ static u16 pxav1_readw(struct sdhci_host *host, int reg)
 	return readw(host->ioaddr + reg);
 }
 
+static u32 pxav1_irq(struct sdhci_host *host, u32 intmask)
+{
+	struct sdhci_pxav2_host *pxav2_host = sdhci_pltfm_priv(sdhci_priv(host));
+	struct mmc_request *sdio_mrq;
+
+	if (pxav2_host->sdio_mrq && (intmask & SDHCI_INT_CMD_MASK)) {
+		/* The dummy CMD0 for the SDIO workaround just completed */
+		sdhci_writel(host, intmask & SDHCI_INT_CMD_MASK, SDHCI_INT_STATUS);
+		intmask &= ~SDHCI_INT_CMD_MASK;
+		sdio_mrq = pxav2_host->sdio_mrq;
+		pxav2_host->sdio_mrq = NULL;
+		mmc_request_done(host->mmc, sdio_mrq);
+	}
+
+	return intmask;
+}
+
+static void pxav1_request_done(struct sdhci_host *host, struct mmc_request *mrq)
+{
+	u16 tmp;
+	struct sdhci_pxav2_host *pxav2_host;
+
+	/* If this is an SDIO command, perform errata workaround for silicon bug */
+	if (mrq->cmd && !mrq->cmd->error &&
+	    (mrq->cmd->opcode == SD_IO_RW_DIRECT ||
+	     mrq->cmd->opcode == SD_IO_RW_EXTENDED)) {
+		/* Reset data port */
+		tmp = readw(host->ioaddr + SDHCI_TIMEOUT_CONTROL);
+		tmp |= 0x400;
+		writew(tmp, host->ioaddr + SDHCI_TIMEOUT_CONTROL);
+
+		/* Clock is now stopped, so restart it by sending a dummy CMD0 */
+		pxav2_host = sdhci_pltfm_priv(sdhci_priv(host));
+		pxav2_host->sdio_mrq = mrq;
+		sdhci_writel(host, 0, SDHCI_ARGUMENT);
+		sdhci_writew(host, 0, SDHCI_TRANSFER_MODE);
+		sdhci_writew(host, SDHCI_MAKE_CMD(MMC_GO_IDLE_STATE, SDHCI_CMD_RESP_NONE),
+			     SDHCI_COMMAND);
+
+		/* Don't finish this request until the dummy CMD0 finishes */
+		return;
+	}
+
+	mmc_request_done(host->mmc, mrq);
+}
+
 static void pxav2_mmc_set_bus_width(struct sdhci_host *host, int width)
 {
 	u8 ctrl;
@@ -118,10 +170,12 @@ struct sdhci_pxa_variant {
 static const struct sdhci_ops pxav1_sdhci_ops = {
 	.read_w        = pxav1_readw,
 	.set_clock     = sdhci_set_clock,
+	.irq           = pxav1_irq,
 	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
 	.set_bus_width = pxav2_mmc_set_bus_width,
 	.reset         = pxav2_reset,
 	.set_uhs_signaling = sdhci_set_uhs_signaling,
+	.request_done  = pxav1_request_done,
 };
 
 static const struct sdhci_pxa_variant __maybe_unused pxav1_variant = {
@@ -193,7 +247,7 @@ static int sdhci_pxav2_probe(struct platform_device *pdev)
 	int ret;
 	struct clk *clk, *clk_core;
 
-	host = sdhci_pltfm_init(pdev, NULL, 0);
+	host = sdhci_pltfm_init(pdev, NULL, sizeof(struct sdhci_pxav2_host));
 	if (IS_ERR(host))
 		return PTR_ERR(host);