linux-kernel - [PATCH 6/9] spi: meson-spicc: setup IO line delay

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Message-Id: <20200312133131.26430-7-narmstrong@baylibre.com>
Date:   Thu, 12 Mar 2020 14:31:28 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     broonie@...nel.org
Cc:     Neil Armstrong <narmstrong@...libre.com>,
        linux-spi@...r.kernel.org, linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 6/9] spi: meson-spicc: setup IO line delay

Now the controller can support frequencies higher than 30MHz, we need
the setup the I/O line delays in regard of the SPI clock frequency.

Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
---
 drivers/spi/spi-meson-spicc.c | 61 ++++++++++++++++++++++++++++++++++-
 1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
index b5bd3a897e8f..4494a791f4a7 100644
--- a/drivers/spi/spi-meson-spicc.c
+++ b/drivers/spi/spi-meson-spicc.c
@@ -106,7 +106,21 @@
 #define SPICC_SWAP_RO		BIT(14) /* RX FIFO Data Swap Read-Only */
 #define SPICC_SWAP_W1		BIT(15) /* RX FIFO Data Swap Write-Only */
 #define SPICC_DLYCTL_RO_MASK	GENMASK(20, 15) /* Delay Control Read-Only */
-#define SPICC_DLYCTL_W1_MASK	GENMASK(21, 16) /* Delay Control Write-Only */
+#define SPICC_MO_DELAY_MASK	GENMASK(17, 16) /* Master Output Delay */
+#define SPICC_MO_NO_DELAY	0
+#define SPICC_MO_DELAY_1_CYCLE	1
+#define SPICC_MO_DELAY_2_CYCLE	2
+#define SPICC_MO_DELAY_3_CYCLE	3
+#define SPICC_MI_DELAY_MASK	GENMASK(19, 18) /* Master Input Delay */
+#define SPICC_MI_NO_DELAY	0
+#define SPICC_MI_DELAY_1_CYCLE	1
+#define SPICC_MI_DELAY_2_CYCLE	2
+#define SPICC_MI_DELAY_3_CYCLE	3
+#define SPICC_MI_CAP_DELAY_MASK	GENMASK(21, 20) /* Master Capture Delay */
+#define SPICC_CAP_AHEAD_2_CYCLE	0
+#define SPICC_CAP_AHEAD_1_CYCLE	1
+#define SPICC_CAP_NO_DELAY	2
+#define SPICC_CAP_DELAY_1_CYCLE	3
 #define SPICC_FIFORST_RO_MASK	GENMASK(22, 21) /* FIFO Softreset Read-Only */
 #define SPICC_FIFORST_W1_MASK	GENMASK(23, 22) /* FIFO Softreset Write-Only */
 
@@ -328,6 +342,49 @@ static irqreturn_t meson_spicc_irq(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+static void meson_spicc_auto_io_delay(struct meson_spicc_device *spicc)
+{
+	u32 div, hz;
+	u32 mi_delay, cap_delay;
+	u32 conf;
+
+	if (spicc->data->has_enhance_clk_div) {
+		div = FIELD_GET(SPICC_ENH_DATARATE_MASK,
+				readl_relaxed(spicc->base + SPICC_ENH_CTL0));
+		div++;
+		div <<= 1;
+	} else {
+		div = FIELD_GET(SPICC_DATARATE_MASK,
+				readl_relaxed(spicc->base + SPICC_CONREG));
+		div += 2;
+		div = 1 << div;
+	}
+
+	mi_delay = SPICC_MI_NO_DELAY;
+	cap_delay = SPICC_CAP_AHEAD_2_CYCLE;
+	hz = clk_get_rate(spicc->clk);
+
+	if (hz >= 100000000)
+		cap_delay = SPICC_CAP_DELAY_1_CYCLE;
+	else if (hz >= 80000000)
+		cap_delay = SPICC_CAP_NO_DELAY;
+	else if (hz >= 40000000)
+		cap_delay = SPICC_CAP_AHEAD_1_CYCLE;
+	else if (div >= 16)
+		mi_delay = SPICC_MI_DELAY_3_CYCLE;
+	else if (div >= 8)
+		mi_delay = SPICC_MI_DELAY_2_CYCLE;
+	else if (div >= 6)
+		mi_delay = SPICC_MI_DELAY_1_CYCLE;
+
+	conf = readl_relaxed(spicc->base + SPICC_TESTREG);
+	conf &= ~(SPICC_MO_DELAY_MASK | SPICC_MI_DELAY_MASK
+		  | SPICC_MI_CAP_DELAY_MASK);
+	conf |= FIELD_PREP(SPICC_MI_DELAY_MASK, mi_delay);
+	conf |= FIELD_PREP(SPICC_MI_CAP_DELAY_MASK, cap_delay);
+	writel_relaxed(conf, spicc->base + SPICC_TESTREG);
+}
+
 static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
 				   struct spi_transfer *xfer)
 {
@@ -346,6 +403,8 @@ static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
 		writel_relaxed(conf, spicc->base + SPICC_CONREG);
 
 	clk_set_rate(spicc->clk, xfer->speed_hz);
+
+	meson_spicc_auto_io_delay(spicc);
 }
 
 static int meson_spicc_transfer_one(struct spi_master *master,
-- 
2.22.0