linux-kernel - [PATCH 2/3] spi: meson-axg: enhance output enable feature

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Message-ID: <20180503213645.20694-3-yixun.lan@amlogic.com>
Date:   Thu, 3 May 2018 21:36:43 +0000
From:   Yixun Lan <yixun.lan@...ogic.com>
To:     Mark Brown <broonie@...nel.org>
CC:     Sunny Luo <sunny.luo@...ogic.com>,
        Yixun Lan <yixun.lan@...ogic.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>, <linux-spi@...r.kernel.org>,
        <linux-amlogic@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/3] spi: meson-axg: enhance output enable feature

From: Sunny Luo <sunny.luo@...ogic.com>

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: Sunny Luo <sunny.luo@...ogic.com>
Signed-off-by: Yixun Lan <yixun.lan@...ogic.com>
---
 drivers/spi/spi-meson-spicc.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
index 8489f4c9f465..90b15f7d50dd 100644
--- a/drivers/spi/spi-meson-spicc.c
+++ b/drivers/spi/spi-meson-spicc.c
@@ -115,6 +115,13 @@
 
 #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)
 
@@ -123,6 +130,7 @@
 
 struct meson_spicc_data {
 	unsigned int			max_speed_hz;
+	bool				has_oen;
 };
 
 struct meson_spicc_device {
@@ -145,6 +153,19 @@ 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,
@@ -453,6 +474,8 @@ static int meson_spicc_prepare_message(struct spi_master *master,
 
 	writel_bits_relaxed(BIT(24), BIT(24), spicc->base + SPICC_TESTREG);
 
+	meson_spicc_oen_enable(spicc);
+
 	return 0;
 }
 
@@ -605,11 +628,12 @@ static int meson_spicc_remove(struct platform_device *pdev)
 }
 
 static const struct meson_spicc_data meson_spicc_gx_data = {
-	.max_speed_hz	= 30000000,
+	.max_speed_hz		= 30000000,
 };
 
 static const struct meson_spicc_data meson_spicc_axg_data = {
-	.max_speed_hz	= 80000000,
+	.max_speed_hz		= 80000000,
+	.has_oen		= true,
 };
 
 static const struct of_device_id meson_spicc_of_match[] = {
-- 
2.17.0