Message-Id: <2dab4859c89a6091f196e7dc43964606bf7a8cf4.1534423916.git.baolin.wang@linaro.org>
Date:   Thu, 16 Aug 2018 20:54:51 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     broonie@...nel.org, robh+dt@...nel.org, mark.rutland@....com
Cc:     orsonzhai@...il.com, zhang.lyra@...il.com,
        lanqing.liu@...eadtrum.com, baolin.wang@...aro.org,
        linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] spi: sprd: Add SPI driver for Spreadtrum SC9860

From: Lanqing Liu <lanqing.liu@...eadtrum.com>

This patch adds the SPI controller driver for Spreadtrum SC9860 platform.

Signed-off-by: Lanqing Liu <lanqing.liu@...eadtrum.com>
Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
---
Changes from v1:
 - Enable the auto_runtime_pm of SPI core.
 - Remove the sprd_spi_setup() function.
 - Move the hardware SPI hardware initialization to transfer setup function.
 - Modify the SPI speed calculation formula.
 - Add one hw_speed_hz field to save the real SPI line speed.
 - Optimize the method of the spi_max_speed variable initialization.
 - Optimize the word delay time.
 - Fix some coding style issues.
---
 drivers/spi/Kconfig    |    6 +
 drivers/spi/Makefile   |    1 +
 drivers/spi/spi-sprd.c |  745 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 752 insertions(+)
 create mode 100644 drivers/spi/spi-sprd.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index ad5d68e..c49c40c 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -596,6 +596,12 @@ config SPI_SIRF
 	help
 	  SPI driver for CSR SiRFprimaII SoCs
 
+config SPI_SPRD
+	tristate "Spreadtrum SPI controller"
+	depends on ARCH_SPRD || COMPILE_TEST
+	help
+	  SPI driver for Spreadtrum SoCs.
+
 config SPI_SPRD_ADI
 	tristate "Spreadtrum ADI controller"
 	depends on ARCH_SPRD || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index cb1f437..5bb6b37 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -88,6 +88,7 @@ obj-$(CONFIG_SPI_SH_HSPI)		+= spi-sh-hspi.o
 obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIRF)		+= spi-sirf.o
+obj-$(CONFIG_SPI_SPRD)			+= spi-sprd.o
 obj-$(CONFIG_SPI_SPRD_ADI)		+= spi-sprd-adi.o
 obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o
 obj-$(CONFIG_SPI_ST_SSC4)		+= spi-st-ssc4.o
diff --git a/drivers/spi/spi-sprd.c b/drivers/spi/spi-sprd.c
new file mode 100644
index 0000000..a9a6c5e
--- /dev/null
+++ b/drivers/spi/spi-sprd.c
@@ -0,0 +1,745 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Spreadtrum Communications Inc.
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.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/pm_runtime.h>
+#include <linux/spi/spi.h>
+
+#define SPRD_SPI_TXD			0x0
+#define SPRD_SPI_CLKD			0x4
+#define SPRD_SPI_CTL0			0x8
+#define SPRD_SPI_CTL1			0xc
+#define SPRD_SPI_CTL2			0x10
+#define SPRD_SPI_CTL3			0x14
+#define SPRD_SPI_CTL4			0x18
+#define SPRD_SPI_CTL5			0x1c
+#define SPRD_SPI_INT_EN			0x20
+#define SPRD_SPI_INT_CLR		0x24
+#define SPRD_SPI_INT_RAW_STS		0x28
+#define SPRD_SPI_INT_MASK_STS		0x2c
+#define SPRD_SPI_STS1			0x30
+#define SPRD_SPI_STS2			0x34
+#define SPRD_SPI_DSP_WAIT		0x38
+#define SPRD_SPI_STS3			0x3c
+#define SPRD_SPI_CTL6			0x40
+#define SPRD_SPI_STS4			0x44
+#define SPRD_SPI_FIFO_RST		0x48
+#define SPRD_SPI_CTL7			0x4c
+#define SPRD_SPI_STS5			0x50
+#define SPRD_SPI_CTL8			0x54
+#define SPRD_SPI_CTL9			0x58
+#define SPRD_SPI_CTL10			0x5c
+#define SPRD_SPI_CTL11			0x60
+#define SPRD_SPI_CTL12			0x64
+#define SPRD_SPI_STS6			0x68
+#define SPRD_SPI_STS7			0x6c
+#define SPRD_SPI_STS8			0x70
+#define SPRD_SPI_STS9			0x74
+
+/* Bits & mask definition for register CTL0 */
+#define SPRD_SPI_SCK_REV		BIT(13)
+#define SPRD_SPI_NG_TX			BIT(1)
+#define SPRD_SPI_NG_RX			BIT(0)
+#define SPRD_SPI_CHNL_LEN_MASK		GENMASK(4, 0)
+#define SPRD_SPI_CSN_MASK		GENMASK(11, 8)
+#define SPRD_SPI_CS0_VALID		BIT(8)
+
+/* Bits & mask definition for register SPI_INT_EN */
+#define SPRD_SPI_TX_END_INT_EN		BIT(8)
+#define SPRD_SPI_RX_END_INT_EN		BIT(9)
+
+/* Bits & mask definition for register SPI_INT_RAW_STS */
+#define SPRD_SPI_TX_END_RAW		BIT(8)
+#define SPRD_SPI_RX_END_RAW		BIT(9)
+
+/* Bits & mask definition for register SPI_INT_CLR */
+#define SPRD_SPI_TX_END_CLR		BIT(8)
+#define SPRD_SPI_RX_END_CLR		BIT(9)
+
+/* Bits & mask definition for register INT_MASK_STS */
+#define SPRD_SPI_MASK_RX_END		BIT(9)
+#define SPRD_SPI_MASK_TX_END		BIT(8)
+
+/* Bits & mask definition for register STS2 */
+#define SPRD_SPI_TX_BUSY		BIT(8)
+
+/* Bits & mask definition for register CTL1 */
+#define SPRD_SPI_RX_MODE		BIT(12)
+#define SPRD_SPI_TX_MODE		BIT(13)
+#define SPRD_SPI_RTX_MD_MASK		GENMASK(13, 12)
+
+/* Bits & mask definition for register CTL2 */
+#define SPRD_SPI_DMA_EN			BIT(6)
+
+/* Bits & mask definition for register CTL4 */
+#define SPRD_SPI_START_RX		BIT(9)
+#define SPRD_SPI_ONLY_RECV_MASK		GENMASK(8, 0)
+
+/* Bits & mask definition for register SPI_INT_CLR */
+#define SPRD_SPI_RX_END_INT_CLR		BIT(9)
+#define SPRD_SPI_TX_END_INT_CLR		BIT(8)
+
+/* Bits & mask definition for register SPI_INT_RAW */
+#define SPRD_SPI_RX_END_IRQ		BIT(9)
+#define SPRD_SPI_TX_END_IRQ		BIT(8)
+
+/* Bits & mask definition for register CTL12 */
+#define SPRD_SPI_SW_RX_REQ		BIT(0)
+#define SPRD_SPI_SW_TX_REQ		BIT(1)
+
+/* Bits & mask definition for register CTL7 */
+#define SPRD_SPI_DATA_LINE2_EN		BIT(15)
+#define SPRD_SPI_MODE_MASK		GENMASK(5, 3)
+#define SPRD_SPI_MODE_OFFSET		3
+#define SPRD_SPI_3WIRE_MODE		4
+#define SPRD_SPI_4WIRE_MODE		0
+
+/* Bits & mask definition for register CTL8 */
+#define SPRD_SPI_TX_MAX_LEN_MASK	GENMASK(19, 0)
+#define SPRD_SPI_TX_LEN_H_MASK		GENMASK(3, 0)
+#define SPRD_SPI_TX_LEN_H_OFFSET	16
+
+/* Bits & mask definition for register CTL9 */
+#define SPRD_SPI_TX_LEN_L_MASK		GENMASK(15, 0)
+
+/* Bits & mask definition for register CTL10 */
+#define SPRD_SPI_RX_MAX_LEN_MASK	GENMASK(19, 0)
+#define SPRD_SPI_RX_LEN_H_MASK		GENMASK(3, 0)
+#define SPRD_SPI_RX_LEN_H_OFFSET	16
+
+/* Bits & mask definition for register CTL11 */
+#define SPRD_SPI_RX_LEN_L_MASK		GENMASK(15, 0)
+
+/* Default & maximum word delay cycles */
+#define SPRD_SPI_MIN_DELAY_CYCLE	14
+#define SPRD_SPI_MAX_DELAY_CYCLE	130
+
+#define SPRD_SPI_FIFO_SIZE		32
+#define SPRD_SPI_CHIP_CS_NUM		0x4
+#define SPRD_SPI_CHNL_LEN		2
+#define SPRD_SPI_DEFAULT_SOURCE		26000000
+#define SPRD_SPI_MAX_SPEED_HZ		48000000
+#define SPRD_SPI_AUTOSUSPEND_DELAY	100
+
+struct sprd_spi {
+	void __iomem *base;
+	struct device *dev;
+	struct clk *clk;
+	u32 src_clk;
+	u32 hw_mode;
+	u32 trans_len;
+	u32 trans_mode;
+	u32 word_delay;
+	u32 hw_speed_hz;
+	u32 len;
+	int status;
+	const void *tx_buf;
+	void *rx_buf;
+	int (*read_bufs)(struct sprd_spi *ss, u32 len);
+	int (*write_bufs)(struct sprd_spi *ss, u32 len);
+};
+
+static u32 sprd_spi_transfer_max_timeout(struct sprd_spi *ss,
+					 struct spi_transfer *t)
+{
+	/*
+	 * The time spent on transmission of the full FIFO data is the maximum
+	 * SPI transmission time.
+	 */
+	u32 size = t->bits_per_word * SPRD_SPI_FIFO_SIZE;
+	u32 bit_time_us = DIV_ROUND_UP(USEC_PER_SEC, ss->hw_speed_hz);
+	u32 total_time_us = size * bit_time_us;
+	/*
+	 * There is an interval between data and the data in our SPI hardware,
+	 * so the total transmission time need add the interval time.
+	 */
+	u32 interval_cycle = SPRD_SPI_FIFO_SIZE * ss->word_delay;
+	u32 interval_time_us = DIV_ROUND_UP(interval_cycle * USEC_PER_SEC,
+					    ss->src_clk);
+
+	return total_time_us + interval_time_us;
+}
+
+static int sprd_spi_wait_for_tx_end(struct sprd_spi *ss, struct spi_transfer *t)
+{
+	u32 val, us;
+	int ret;
+
+	us = sprd_spi_transfer_max_timeout(ss, t);
+	ret = readl_relaxed_poll_timeout(ss->base + SPRD_SPI_INT_RAW_STS, val,
+					 val & SPRD_SPI_TX_END_IRQ, 0, us);
+	if (ret) {
+		dev_err(ss->dev, "SPI error, spi send timeout!\n");
+		return ret;
+	}
+
+	ret = readl_relaxed_poll_timeout(ss->base + SPRD_SPI_STS2, val,
+					 !(val & SPRD_SPI_TX_BUSY), 0, us);
+	if (ret) {
+		dev_err(ss->dev, "SPI error, spi busy timeout!\n");
+		return ret;
+	}
+
+	writel_relaxed(SPRD_SPI_TX_END_INT_CLR, ss->base + SPRD_SPI_INT_CLR);
+
+	return 0;
+}
+
+static int sprd_spi_wait_for_rx_end(struct sprd_spi *ss, struct spi_transfer *t)
+{
+	u32 val, us;
+	int ret;
+
+	us = sprd_spi_transfer_max_timeout(ss, t);
+	ret = readl_relaxed_poll_timeout(ss->base + SPRD_SPI_INT_RAW_STS, val,
+					 val & SPRD_SPI_RX_END_IRQ, 0, us);
+	if (ret) {
+		dev_err(ss->dev, "SPI error, spi rx timeout!\n");
+		return ret;
+	}
+
+	writel_relaxed(SPRD_SPI_RX_END_INT_CLR, ss->base + SPRD_SPI_INT_CLR);
+
+	return 0;
+}
+
+static void sprd_spi_tx_req(struct sprd_spi *ss)
+{
+	writel_relaxed(SPRD_SPI_SW_TX_REQ, ss->base + SPRD_SPI_CTL12);
+}
+
+static void sprd_spi_rx_req(struct sprd_spi *ss)
+{
+	writel_relaxed(SPRD_SPI_SW_RX_REQ, ss->base + SPRD_SPI_CTL12);
+}
+
+static void sprd_spi_enter_idle(struct sprd_spi *ss)
+{
+	u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL1);
+
+	val &= ~SPRD_SPI_RTX_MD_MASK;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL1);
+}
+
+static void sprd_spi_set_transfer_bits(struct sprd_spi *ss, u32 bits)
+{
+	u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL0);
+
+	/* Set the valid bits for every transaction */
+	val &= ~(SPRD_SPI_CHNL_LEN_MASK << SPRD_SPI_CHNL_LEN);
+	val |= bits << SPRD_SPI_CHNL_LEN;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL0);
+}
+
+static void sprd_spi_set_tx_length(struct sprd_spi *ss, u32 length)
+{
+	u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL8);
+
+	length &= SPRD_SPI_TX_MAX_LEN_MASK;
+	val &= ~SPRD_SPI_TX_LEN_H_MASK;
+	val |= length >> SPRD_SPI_TX_LEN_H_OFFSET;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL8);
+
+	val = length & SPRD_SPI_TX_LEN_L_MASK;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL9);
+}
+
+static void sprd_spi_set_rx_length(struct sprd_spi *ss, u32 length)
+{
+	u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL10);
+
+	length &= SPRD_SPI_RX_MAX_LEN_MASK;
+	val &= ~SPRD_SPI_RX_LEN_H_MASK;
+	val |= length >> SPRD_SPI_RX_LEN_H_OFFSET;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL10);
+
+	val = length & SPRD_SPI_RX_LEN_L_MASK;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL11);
+}
+
+static void sprd_spi_chipselect(struct spi_device *sdev, bool cs)
+{
+	struct spi_controller *sctlr = sdev->controller;
+	struct sprd_spi *ss = spi_controller_get_devdata(sctlr);
+	u32 val;
+
+	val = readl_relaxed(ss->base + SPRD_SPI_CTL0);
+	/*  The SPI controller will pull down CS pin if cs is 0 */
+	if (!cs) {
+		val &= ~SPRD_SPI_CS0_VALID;
+		writel_relaxed(val, ss->base + SPRD_SPI_CTL0);
+	} else {
+		val |= SPRD_SPI_CSN_MASK;
+		writel_relaxed(val, ss->base + SPRD_SPI_CTL0);
+	}
+}
+
+static int sprd_spi_write_only_receive(struct sprd_spi *ss, u32 len)
+{
+	u32 val;
+
+	/* Clear the start receive bit and reset receive data number */
+	val = readl_relaxed(ss->base + SPRD_SPI_CTL4);
+	val &= ~(SPRD_SPI_START_RX | SPRD_SPI_ONLY_RECV_MASK);
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL4);
+
+	/* Set the receive data length */
+	val = readl_relaxed(ss->base + SPRD_SPI_CTL4);
+	val |= len & SPRD_SPI_ONLY_RECV_MASK;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL4);
+
+	/* Trigger to receive data */
+	val = readl_relaxed(ss->base + SPRD_SPI_CTL4);
+	val |= SPRD_SPI_START_RX;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL4);
+
+	return len;
+}
+
+static int sprd_spi_write_bufs_u8(struct sprd_spi *ss, u32 len)
+{
+	u8 *tx_p = (u8 *)ss->tx_buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		writeb_relaxed(tx_p[i], ss->base + SPRD_SPI_TXD);
+
+	ss->tx_buf += i;
+	return i;
+}
+
+static int sprd_spi_write_bufs_u16(struct sprd_spi *ss, u32 len)
+{
+	u16 *tx_p = (u16 *)ss->tx_buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		writew_relaxed(tx_p[i], ss->base + SPRD_SPI_TXD);
+
+	ss->tx_buf += i << 1;
+	return i << 1;
+}
+
+static int sprd_spi_write_bufs_u32(struct sprd_spi *ss, u32 len)
+{
+	u32 *tx_p = (u32 *)ss->tx_buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		writel_relaxed(tx_p[i], ss->base + SPRD_SPI_TXD);
+
+	ss->tx_buf += i << 2;
+	return i << 2;
+}
+
+static int sprd_spi_read_bufs_u8(struct sprd_spi *ss, u32 len)
+{
+	u8 *rx_p = (u8 *)ss->rx_buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		rx_p[i] = readb_relaxed(ss->base + SPRD_SPI_TXD);
+
+	ss->rx_buf += i;
+	return i;
+}
+
+static int sprd_spi_read_bufs_u16(struct sprd_spi *ss, u32 len)
+{
+	u16 *rx_p = (u16 *)ss->rx_buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		rx_p[i] = readw_relaxed(ss->base + SPRD_SPI_TXD);
+
+	ss->rx_buf += i << 1;
+	return i << 1;
+}
+
+static int sprd_spi_read_bufs_u32(struct sprd_spi *ss, u32 len)
+{
+	u32 *rx_p = (u32 *)ss->rx_buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		rx_p[i] = readl_relaxed(ss->base + SPRD_SPI_TXD);
+
+	ss->rx_buf += i << 2;
+	return i << 2;
+}
+
+static int sprd_spi_txrx_bufs(struct spi_device *sdev, struct spi_transfer *t)
+{
+	struct sprd_spi *ss = spi_controller_get_devdata(sdev->controller);
+	u32 trans_len = ss->trans_len, len;
+	int ret, write_size = 0;
+
+	while (trans_len) {
+		len = trans_len > SPRD_SPI_FIFO_SIZE ? SPRD_SPI_FIFO_SIZE :
+			trans_len;
+		if (ss->trans_mode & SPRD_SPI_TX_MODE) {
+			sprd_spi_set_tx_length(ss, len);
+			write_size += ss->write_bufs(ss, len);
+
+			/*
+			 * For our 3 wires mode or dual TX line mode, we need
+			 * to request the controller to transfer.
+			 */
+			if (ss->hw_mode & SPI_3WIRE || ss->hw_mode & SPI_TX_DUAL)
+				sprd_spi_tx_req(ss);
+
+			ret = sprd_spi_wait_for_tx_end(ss, t);
+		} else {
+			sprd_spi_set_rx_length(ss, len);
+
+			/*
+			 * For our 3 wires mode or dual TX line mode, we need
+			 * to request the controller to read.
+			 */
+			if (ss->hw_mode & SPI_3WIRE || ss->hw_mode & SPI_TX_DUAL)
+				sprd_spi_rx_req(ss);
+			else
+				write_size += ss->write_bufs(ss, len);
+
+			ret = sprd_spi_wait_for_rx_end(ss, t);
+		}
+
+		if (ret)
+			goto complete;
+
+		if (ss->trans_mode & SPRD_SPI_RX_MODE)
+			ss->read_bufs(ss, len);
+
+		trans_len -= len;
+	}
+
+	ret = write_size;
+
+complete:
+	sprd_spi_enter_idle(ss);
+
+	return ret;
+}
+
+static void sprd_spi_set_speed(struct sprd_spi *ss, u32 speed_hz)
+{
+	/*
+	 * From SPI datasheet, the prescale calculation formula:
+	 * prescale = SPI source clock / (2 * SPI_freq) - 1;
+	 */
+	u32 clk_div = DIV_ROUND_UP(ss->src_clk, speed_hz << 1) - 1;
+
+	/* Save the real hardware speed */
+	ss->hw_speed_hz = (ss->src_clk >> 1) / (clk_div + 1);
+	writel_relaxed(clk_div, ss->base + SPRD_SPI_CLKD);
+}
+
+static void sprd_spi_init_hw(struct sprd_spi *ss, struct spi_transfer *t)
+{
+	u16 word_delay, interval;
+	u32 val;
+
+	val = readl_relaxed(ss->base + SPRD_SPI_CTL7);
+	val &= ~(SPRD_SPI_SCK_REV | SPRD_SPI_NG_TX | SPRD_SPI_NG_RX);
+	/* Set default chip selection, clock phase and clock polarity */
+	val |= ss->hw_mode & SPI_CPHA ? SPRD_SPI_NG_RX : SPRD_SPI_NG_TX;
+	val |= ss->hw_mode & SPI_CPOL ? SPRD_SPI_SCK_REV : 0;
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL0);
+
+	/*
+	 * Set the intervals of two SPI frames, and the inteval calculation
+	 * formula as below per datasheet:
+	 * interval time (source clock cycles) = interval * 4 + 10.
+	 */
+	word_delay = clamp_t(u16, t->word_delay, SPRD_SPI_MIN_DELAY_CYCLE,
+			     SPRD_SPI_MAX_DELAY_CYCLE);
+	interval = DIV_ROUND_UP(word_delay - 10, 4);
+	ss->word_delay = interval * 4 + 10;
+	writel_relaxed(interval, ss->base + SPRD_SPI_CTL5);
+
+	/* Reset SPI fifo */
+	writel_relaxed(1, ss->base + SPRD_SPI_FIFO_RST);
+	writel_relaxed(0, ss->base + SPRD_SPI_FIFO_RST);
+
+	/* Set SPI work mode */
+	val = readl_relaxed(ss->base + SPRD_SPI_CTL7);
+	val &= ~SPRD_SPI_MODE_MASK;
+
+	if (ss->hw_mode & SPI_3WIRE)
+		val |= SPRD_SPI_3WIRE_MODE << SPRD_SPI_MODE_OFFSET;
+	else
+		val |= SPRD_SPI_4WIRE_MODE << SPRD_SPI_MODE_OFFSET;
+
+	if (ss->hw_mode & SPI_TX_DUAL)
+		val |= SPRD_SPI_DATA_LINE2_EN;
+	else
+		val &= ~SPRD_SPI_DATA_LINE2_EN;
+
+	writel_relaxed(val, ss->base + SPRD_SPI_CTL7);
+}
+
+static int sprd_spi_setup_transfer(struct spi_device *sdev,
+				   struct spi_transfer *t)
+{
+	struct sprd_spi *ss = spi_controller_get_devdata(sdev->controller);
+	u8 bits_per_word = t->bits_per_word;
+	u32 val, mode = 0;
+
+	ss->len = t->len;
+	ss->tx_buf = t->tx_buf;
+	ss->rx_buf = t->rx_buf;
+
+	ss->hw_mode = sdev->mode;
+	sprd_spi_init_hw(ss, t);
+
+	/* Set tansfer speed and valid bits */
+	sprd_spi_set_speed(ss, t->speed_hz);
+	sprd_spi_set_transfer_bits(ss, bits_per_word);
+
+	if (bits_per_word > 16)
+		bits_per_word = round_up(bits_per_word, 16);
+	else
+		bits_per_word = round_up(bits_per_word, 8);
+
+	switch (bits_per_word) {
+	case 8:
+		ss->trans_len = t->len;
+		ss->read_bufs = sprd_spi_read_bufs_u8;
+		ss->write_bufs = sprd_spi_write_bufs_u8;
+		break;
+	case 16:
+		ss->trans_len = t->len >> 1;
+		ss->read_bufs = sprd_spi_read_bufs_u16;
+		ss->write_bufs = sprd_spi_write_bufs_u16;
+		break;
+	case 32:
+		ss->trans_len = t->len >> 2;
+		ss->read_bufs = sprd_spi_read_bufs_u32;
+		ss->write_bufs = sprd_spi_write_bufs_u32;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Set transfer read or write mode */
+	val = readl_relaxed(ss->base + SPRD_SPI_CTL1);
+	val &= ~SPRD_SPI_RTX_MD_MASK;
+	if (t->tx_buf)
+		mode |= SPRD_SPI_TX_MODE;
+	if (t->rx_buf)
+		mode |= SPRD_SPI_RX_MODE;
+
+	writel_relaxed(val | mode, ss->base + SPRD_SPI_CTL1);
+
+	ss->trans_mode = mode;
+
+	/*
+	 * If in only receive mode, we need to trigger the SPI controller to
+	 * receive data automatically.
+	 */
+	if (ss->trans_mode == SPRD_SPI_RX_MODE)
+		ss->write_bufs = sprd_spi_write_only_receive;
+
+	return 0;
+}
+
+static int sprd_spi_transfer_one(struct spi_controller *sctlr,
+				 struct spi_device *sdev,
+				 struct spi_transfer *t)
+{
+	int ret;
+
+	ret = sprd_spi_setup_transfer(sdev, t);
+	if (ret)
+		goto setup_err;
+
+	ret = sprd_spi_txrx_bufs(sdev, t);
+	if (ret == t->len)
+		ret = 0;
+	else if (ret >= 0)
+		ret = -EREMOTEIO;
+
+setup_err:
+	spi_finalize_current_transfer(sctlr);
+
+	return ret;
+}
+
+static int sprd_spi_clk_init(struct platform_device *pdev, struct sprd_spi *ss)
+{
+	struct clk *clk_spi, *clk_parent;
+
+	clk_spi = devm_clk_get(&pdev->dev, "spi");
+	if (IS_ERR(clk_spi)) {
+		dev_warn(&pdev->dev, "can't get the spi clock\n");
+		clk_spi = NULL;
+	}
+
+	clk_parent = devm_clk_get(&pdev->dev, "source");
+	if (IS_ERR(clk_parent)) {
+		dev_warn(&pdev->dev, "can't get the source clock\n");
+		clk_parent = NULL;
+	}
+
+	ss->clk = devm_clk_get(&pdev->dev, "enable");
+	if (IS_ERR(ss->clk)) {
+		dev_err(&pdev->dev, "can't get the enable clock\n");
+		return PTR_ERR(ss->clk);
+	}
+
+	if (!clk_set_parent(clk_spi, clk_parent))
+		ss->src_clk = clk_get_rate(clk_spi);
+	else
+		ss->src_clk = SPRD_SPI_DEFAULT_SOURCE;
+
+	return 0;
+}
+
+static int sprd_spi_probe(struct platform_device *pdev)
+{
+	struct spi_controller *sctlr;
+	struct resource *res;
+	struct sprd_spi *ss;
+	int ret;
+
+	pdev->id = of_alias_get_id(pdev->dev.of_node, "spi");
+	sctlr = spi_alloc_master(&pdev->dev, sizeof(*ss));
+	if (!sctlr)
+		return -ENOMEM;
+
+	ss = spi_controller_get_devdata(sctlr);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ss->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ss->base)) {
+		ret = PTR_ERR(ss->base);
+		goto free_controller;
+	}
+
+	ss->dev = &pdev->dev;
+	sctlr->dev.of_node = pdev->dev.of_node;
+	sctlr->mode_bits = SPI_CPOL | SPI_CPHA | SPI_3WIRE | SPI_TX_DUAL;
+	sctlr->bus_num = pdev->id;
+	sctlr->set_cs = sprd_spi_chipselect;
+	sctlr->transfer_one = sprd_spi_transfer_one;
+	sctlr->auto_runtime_pm = true;
+	sctlr->max_speed_hz = min_t(u32, ss->src_clk >> 1,
+				    SPRD_SPI_MAX_SPEED_HZ);
+
+	platform_set_drvdata(pdev, sctlr);
+	ret = sprd_spi_clk_init(pdev, ss);
+	if (ret)
+		goto free_controller;
+
+	ret = clk_prepare_enable(ss->clk);
+	if (ret)
+		goto free_controller;
+
+	ret = pm_runtime_set_active(&pdev->dev);
+	if (ret < 0)
+		goto disable_clk;
+
+	pm_runtime_set_autosuspend_delay(&pdev->dev,
+					 SPRD_SPI_AUTOSUSPEND_DELAY);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+	ret = pm_runtime_get_sync(&pdev->dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to resume SPI controller\n");
+		goto err_rpm_put;
+	}
+
+	ret = devm_spi_register_controller(&pdev->dev, sctlr);
+	if (ret)
+		goto err_rpm_put;
+
+	pm_runtime_mark_last_busy(&pdev->dev);
+	pm_runtime_put_autosuspend(&pdev->dev);
+
+	return 0;
+
+err_rpm_put:
+	pm_runtime_put_noidle(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+disable_clk:
+	clk_disable_unprepare(ss->clk);
+free_controller:
+	spi_controller_put(sctlr);
+
+	return ret;
+}
+
+static int __exit sprd_spi_remove(struct platform_device *pdev)
+{
+	struct spi_controller *sctlr = platform_get_drvdata(pdev);
+	struct sprd_spi *ss = spi_controller_get_devdata(sctlr);
+	int ret;
+
+	ret = pm_runtime_get_sync(ss->dev);
+	if (ret < 0) {
+		dev_err(ss->dev, "failed to resume SPI controller\n");
+		return ret;
+	}
+
+	clk_disable_unprepare(ss->clk);
+	pm_runtime_put_noidle(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
+	return 0;
+}
+
+static int __maybe_unused sprd_spi_runtime_suspend(struct device *dev)
+{
+	struct spi_controller *sctlr = dev_get_drvdata(dev);
+	struct sprd_spi *ss = spi_controller_get_devdata(sctlr);
+
+	clk_disable_unprepare(ss->clk);
+
+	return 0;
+}
+
+static int __maybe_unused sprd_spi_runtime_resume(struct device *dev)
+{
+	struct spi_controller *sctlr = dev_get_drvdata(dev);
+	struct sprd_spi *ss = spi_controller_get_devdata(sctlr);
+	int ret;
+
+	ret = clk_prepare_enable(ss->clk);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct dev_pm_ops sprd_spi_pm_ops = {
+	SET_RUNTIME_PM_OPS(sprd_spi_runtime_suspend,
+			   sprd_spi_runtime_resume, NULL)
+};
+
+static const struct of_device_id sprd_spi_of_match[] = {
+	{ .compatible = "sprd,sc9860-spi", },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver sprd_spi_driver = {
+	.driver = {
+		.name = "sprd-spi",
+		.of_match_table = sprd_spi_of_match,
+		.pm = &sprd_spi_pm_ops,
+	},
+	.probe = sprd_spi_probe,
+	.remove  = sprd_spi_remove,
+};
+
+module_platform_driver(sprd_spi_driver);
+
+MODULE_DESCRIPTION("Spreadtrum SPI Controller driver");
+MODULE_AUTHOR("Lanqing Liu <lanqing.liu@...eadtrum.com>");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5

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