spi: meson-spicc: enhance output enable feature

The SPICC controller in Meson-AXG is capable of driving the CLK/MOSI/SS
signal lines through the idle state (between two transmission operation),
which avoid the signals floating in unexpected state.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
Signed-off-by: Sunny Luo <sunny.luo@amlogic.com>
Link: https://lore.kernel.org/r/20200312133131.26430-3-narmstrong@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-meson-spicc.c

@@ -9,11 +9,13 @@
 
 #include <linux/bitfield.h>
 #include <linux/clk.h>
+#include <linux/clk-provider.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/spi/spi.h>
 #include <linux/types.h>
@@ -113,12 +115,23 @@
 
 #define SPICC_DWADDR	0x24	/* Write Address of DMA */
 
+#define SPICC_ENH_CTL0	0x38	/* Enhanced Feature */
+#define SPICC_ENH_MOSI_OEN		BIT(25)
+#define SPICC_ENH_CLK_OEN		BIT(26)
+#define SPICC_ENH_CS_OEN		BIT(27)
+#define SPICC_ENH_CLK_CS_DELAY_EN	BIT(28)
+#define SPICC_ENH_MAIN_CLK_AO		BIT(29)
+
 #define writel_bits_relaxed(mask, val, addr) \
 	writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)
 
 #define SPICC_BURST_MAX	16
 #define SPICC_FIFO_HALF 10
 
+struct meson_spicc_data {
+	bool				has_oen;
+};
+
 struct meson_spicc_device {
 	struct spi_master		*master;
 	struct platform_device		*pdev;
@@ -126,6 +139,7 @@ struct meson_spicc_device {
 	struct clk			*core;
 	struct spi_message		*message;
 	struct spi_transfer		*xfer;
+	const struct meson_spicc_data	*data;
 	u8				*tx_buf;
 	u8				*rx_buf;
 	unsigned int			bytes_per_word;
@@ -136,6 +150,19 @@ struct meson_spicc_device {
 	bool				is_last_burst;
 };
 
+static void meson_spicc_oen_enable(struct meson_spicc_device *spicc)
+{
+	u32 conf;
+
+	if (!spicc->data->has_oen)
+		return;
+
+	conf = readl_relaxed(spicc->base + SPICC_ENH_CTL0) |
+		SPICC_ENH_MOSI_OEN | SPICC_ENH_CLK_OEN | SPICC_ENH_CS_OEN;
+
+	writel_relaxed(conf, spicc->base + SPICC_ENH_CTL0);
+}
+
 static inline bool meson_spicc_txfull(struct meson_spicc_device *spicc)
 {
 	return !!FIELD_GET(SPICC_TF,
@@ -489,6 +516,13 @@ static int meson_spicc_probe(struct platform_device *pdev)
 	spicc = spi_master_get_devdata(master);
 	spicc->master = master;
 
+	spicc->data = of_device_get_match_data(&pdev->dev);
+	if (!spicc->data) {
+		dev_err(&pdev->dev, "failed to get match data\n");
+		ret = -EINVAL;
+		goto out_master;
+	}
+
 	spicc->pdev = pdev;
 	platform_set_drvdata(pdev, spicc);
 
@@ -548,6 +582,8 @@ static int meson_spicc_probe(struct platform_device *pdev)
 	else
 		master->max_speed_hz = rate >> 2;
 
+	meson_spicc_oen_enable(spicc);
+
 	ret = devm_spi_register_master(&pdev->dev, master);
 	if (ret) {
 		dev_err(&pdev->dev, "spi master registration failed\n");
@@ -577,9 +613,22 @@ static int meson_spicc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct meson_spicc_data meson_spicc_gx_data = {
+};
+
+static const struct meson_spicc_data meson_spicc_axg_data = {
+	.has_oen		= true,
+};
+
 static const struct of_device_id meson_spicc_of_match[] = {
-	{ .compatible = "amlogic,meson-gx-spicc", },
-	{ .compatible = "amlogic,meson-axg-spicc", },
+	{
+		.compatible	= "amlogic,meson-gx-spicc",
+		.data		= &meson_spicc_gx_data,
+	},
+	{
+		.compatible = "amlogic,meson-axg-spicc",
+		.data		= &meson_spicc_axg_data,
+	},
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, meson_spicc_of_match);