mmc: sdhci-cadence: Add AMD Pensando Elba SoC support

Add support for AMD Pensando Elba SoC which explicitly
controls byte-lane enables on writes.

Select MMC_SDHCI_IO_ACCESSORS for MMC_SDHCI_CADENCE which
allows Elba SoC sdhci_elba_ops to overwrite the SDHCI
IO memory accessors

Signed-off-by: Brad Larson <blarson@amd.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20230410184526.15990-14-blarson@amd.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/Kconfig

@@ -255,6 +255,7 @@ config MMC_SDHCI_CADENCE
 	tristate "SDHCI support for the Cadence SD/SDIO/eMMC controller"
 	depends on MMC_SDHCI_PLTFM
 	depends on OF
+	select MMC_SDHCI_IO_ACCESSORS
 	help
 	  This selects the Cadence SD/SDIO/eMMC driver.
 

drivers/mmc/host/sdhci-cadence.c

@@ -66,6 +66,8 @@ struct sdhci_cdns_phy_param {
 
 struct sdhci_cdns_priv {
 	void __iomem *hrs_addr;
+	void __iomem *ctl_addr;	/* write control */
+	spinlock_t wrlock;	/* write lock */
 	bool enhanced_strobe;
 	void (*priv_writel)(struct sdhci_cdns_priv *priv, u32 val, void __iomem *reg);
 	unsigned int nr_phy_params;
@@ -321,6 +323,91 @@ static void sdhci_cdns_set_uhs_signaling(struct sdhci_host *host,
 		sdhci_set_uhs_signaling(host, timing);
 }
 
+/* Elba control register bits [6:3] are byte-lane enables */
+#define ELBA_BYTE_ENABLE_MASK(x)	((x) << 3)
+
+/*
+ * The Pensando Elba SoC explicitly controls byte-lane enabling on writes
+ * which includes writes to the HRS registers.  The write lock (wrlock)
+ * is used to ensure byte-lane enable, using write control (ctl_addr),
+ * occurs before the data write.
+ */
+static void elba_priv_writel(struct sdhci_cdns_priv *priv, u32 val,
+			     void __iomem *reg)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->wrlock, flags);
+	writel(GENMASK(7, 3), priv->ctl_addr);
+	writel(val, reg);
+	spin_unlock_irqrestore(&priv->wrlock, flags);
+}
+
+static void elba_write_l(struct sdhci_host *host, u32 val, int reg)
+{
+	elba_priv_writel(sdhci_cdns_priv(host), val, host->ioaddr + reg);
+}
+
+static void elba_write_w(struct sdhci_host *host, u16 val, int reg)
+{
+	struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
+	u32 shift = reg & GENMASK(1, 0);
+	unsigned long flags;
+	u32 byte_enables;
+
+	byte_enables = GENMASK(1, 0) << shift;
+	spin_lock_irqsave(&priv->wrlock, flags);
+	writel(ELBA_BYTE_ENABLE_MASK(byte_enables), priv->ctl_addr);
+	writew(val, host->ioaddr + reg);
+	spin_unlock_irqrestore(&priv->wrlock, flags);
+}
+
+static void elba_write_b(struct sdhci_host *host, u8 val, int reg)
+{
+	struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
+	u32 shift = reg & GENMASK(1, 0);
+	unsigned long flags;
+	u32 byte_enables;
+
+	byte_enables = BIT(0) << shift;
+	spin_lock_irqsave(&priv->wrlock, flags);
+	writel(ELBA_BYTE_ENABLE_MASK(byte_enables), priv->ctl_addr);
+	writeb(val, host->ioaddr + reg);
+	spin_unlock_irqrestore(&priv->wrlock, flags);
+}
+
+static const struct sdhci_ops sdhci_elba_ops = {
+	.write_l = elba_write_l,
+	.write_w = elba_write_w,
+	.write_b = elba_write_b,
+	.set_clock = sdhci_set_clock,
+	.get_timeout_clock = sdhci_cdns_get_timeout_clock,
+	.set_bus_width = sdhci_set_bus_width,
+	.reset = sdhci_reset,
+	.set_uhs_signaling = sdhci_cdns_set_uhs_signaling,
+};
+
+static int elba_drv_init(struct platform_device *pdev)
+{
+	struct sdhci_host *host = platform_get_drvdata(pdev);
+	struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
+	void __iomem *ioaddr;
+
+	host->mmc->caps |= MMC_CAP_1_8V_DDR | MMC_CAP_8_BIT_DATA;
+	spin_lock_init(&priv->wrlock);
+
+	/* Byte-lane control register */
+	ioaddr = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(ioaddr))
+		return PTR_ERR(ioaddr);
+
+	priv->ctl_addr = ioaddr;
+	priv->priv_writel = elba_priv_writel;
+	writel(ELBA_BYTE_ENABLE_MASK(0xf), priv->ctl_addr);
+
+	return 0;
+}
+
 static const struct sdhci_ops sdhci_cdns_ops = {
 	.set_clock = sdhci_set_clock,
 	.get_timeout_clock = sdhci_cdns_get_timeout_clock,
@@ -337,6 +424,13 @@ static const struct sdhci_cdns_drv_data sdhci_cdns_uniphier_drv_data = {
 	},
 };
 
+static const struct sdhci_cdns_drv_data sdhci_elba_drv_data = {
+	.init = elba_drv_init,
+	.pltfm_data = {
+		.ops = &sdhci_elba_ops,
+	},
+};
+
 static const struct sdhci_cdns_drv_data sdhci_cdns_drv_data = {
 	.pltfm_data = {
 		.ops = &sdhci_cdns_ops,
@@ -477,6 +571,10 @@ static const struct of_device_id sdhci_cdns_match[] = {
 		.compatible = "socionext,uniphier-sd4hc",
 		.data = &sdhci_cdns_uniphier_drv_data,
 	},
+	{
+		.compatible = "amd,pensando-elba-sd4hc",
+		.data = &sdhci_elba_drv_data,
+	},
 	{ .compatible = "cdns,sd4hc" },
 	{ /* sentinel */ }
 };