[PATCH v2 1/3] spi: Introduce one new field to set word delay

[PATCH v2 1/3] spi: Introduce one new field to set word delay

[Baolin Wang]

For some SPI controllers, after each word size (specified by bits_per_word)
transimission, the hardware need some delay to make sure the slave has enough
time to receive the whole data.

So introducing one new 'word_delay' field of struct spi_tansfer for slave
devices to set this inter word delay time.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes from v1:
 - New patch in v2.
---
 include/linux/spi/spi.h |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index a64235e..d698f9d 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -711,6 +711,8 @@ extern void spi_res_release(struct spi_controller *ctlr,
  * @delay_usecs: microseconds to delay after this transfer before
  *	(optionally) changing the chipselect status, then starting
  *	the next transfer or completing this @spi_message.
+ * @word_delay: clock cycles to inter word delay after each word size
+ *	(set by bits_per_word) transmission.
  * @transfer_list: transfers are sequenced through @spi_message.transfers
  * @tx_sg: Scatterlist for transmit, currently not for client use
  * @rx_sg: Scatterlist for receive, currently not for client use
@@ -793,6 +795,7 @@ struct spi_transfer {
 	u8		bits_per_word;
 	u16		delay_usecs;
 	u32		speed_hz;
+	u16		word_delay;
 
 	struct list_head transfer_list;
 };
-- 
1.7.9.5

[PATCH v2 2/3] dt-bindings: spi: Add Spreadtrum SPI controller documentation

[Baolin Wang]

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

This patch adds the binding documentation for Spreadtrum SPI
controller device.

Signed-off-by: Lanqing Liu <lanqing.liu@spreadtrum.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes from v1:
 - Remove the sprd,spi-interval property.
---
 Documentation/devicetree/bindings/spi/spi-sprd.txt |   26 ++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/spi-sprd.txt

diff --git a/Documentation/devicetree/bindings/spi/spi-sprd.txt b/Documentation/devicetree/bindings/spi/spi-sprd.txt
new file mode 100644
index 0000000..bad211a
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-sprd.txt
@@ -0,0 +1,26 @@
+Spreadtrum SPI Controller
+
+Required properties:
+- compatible: Should be "sprd,sc9860-spi".
+- reg: Offset and length of SPI controller register space.
+- interrupts: Should contain SPI interrupt.
+- clock-names: Should contain following entries:
+	"spi" for SPI clock,
+	"source" for SPI source (parent) clock,
+	"enable" for SPI module enable clock.
+- clocks: List of clock input name strings sorted in the same order
+	as the clock-names property.
+- #address-cells: The number of cells required to define a chip select
+	address on the SPI bus. Should be set to 1.
+- #size-cells: Should be set to 0.
+
+Example:
+spi0: spi@70a00000{
+	compatible = "sprd,sc9860-spi";
+	reg = <0 0x70a00000 0 0x1000>;
+	interrupts = <GIC_SPI 7 IRQ_TYPE_LEVEL_HIGH>;
+	clock-names = "spi", "source","enable";
+	clocks = <&clk_spi0>, <&ext_26m>, <&clk_ap_apb_gates 5>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+};
-- 
1.7.9.5

[PATCH v2 3/3] spi: sprd: Add SPI driver for Spreadtrum SC9860

[Baolin Wang]

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

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

Signed-off-by: Lanqing Liu <lanqing.liu@spreadtrum.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.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@spreadtrum.com>");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5

Re: [PATCH v2 2/3] dt-bindings: spi: Add Spreadtrum SPI controller documentation

[Rob Herring]

On Thu, 16 Aug 2018 20:54:50 +0800, Baolin Wang wrote:
> From: Lanqing Liu <lanqing.liu@spreadtrum.com>
> 
> This patch adds the binding documentation for Spreadtrum SPI
> controller device.
> 
> Signed-off-by: Lanqing Liu <lanqing.liu@spreadtrum.com>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
> Changes from v1:
>  - Remove the sprd,spi-interval property.
> ---
>  Documentation/devicetree/bindings/spi/spi-sprd.txt |   26 ++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/spi/spi-sprd.txt
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Applied "spi: sprd: Add SPI driver for Spreadtrum SC9860" to the spi tree

[Mark Brown]

The patch

   spi: sprd: Add SPI driver for Spreadtrum SC9860

has been applied to the spi tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From e7d973a31c24b3e82d54b6619f4b633038fce228 Mon Sep 17 00:00:00 2001
From: Lanqing Liu <lanqing.liu@spreadtrum.com>
Date: Thu, 16 Aug 2018 20:54:51 +0800
Subject: [PATCH] spi: sprd: Add SPI driver for Spreadtrum SC9860

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

Signed-off-by: Lanqing Liu <lanqing.liu@spreadtrum.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 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 671d078349cc..7580eb76ab18 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 a90d55970036..1920b6cc2b7e 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 000000000000..a9a6c5ed443f
--- /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@spreadtrum.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.18.0

Applied "spi: Introduce one new field to set word delay" to the spi tree

[Mark Brown]

The patch

   spi: Introduce one new field to set word delay

has been applied to the spi tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From eeaceb8b7d1fb64b6030249ca0dd1d902ef3069e Mon Sep 17 00:00:00 2001
From: Baolin Wang <baolin.wang@linaro.org>
Date: Thu, 16 Aug 2018 20:54:49 +0800
Subject: [PATCH] spi: Introduce one new field to set word delay

For some SPI controllers, after each word size (specified by bits_per_word)
transimission, the hardware need some delay to make sure the slave has enough
time to receive the whole data.

So introducing one new 'word_delay' field of struct spi_tansfer for slave
devices to set this inter word delay time.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 include/linux/spi/spi.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index a64235e05321..d698f9db3484 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -711,6 +711,8 @@ extern void spi_res_release(struct spi_controller *ctlr,
  * @delay_usecs: microseconds to delay after this transfer before
  *	(optionally) changing the chipselect status, then starting
  *	the next transfer or completing this @spi_message.
+ * @word_delay: clock cycles to inter word delay after each word size
+ *	(set by bits_per_word) transmission.
  * @transfer_list: transfers are sequenced through @spi_message.transfers
  * @tx_sg: Scatterlist for transmit, currently not for client use
  * @rx_sg: Scatterlist for receive, currently not for client use
@@ -793,6 +795,7 @@ struct spi_transfer {
 	u8		bits_per_word;
 	u16		delay_usecs;
 	u32		speed_hz;
+	u16		word_delay;
 
 	struct list_head transfer_list;
 };
-- 
2.18.0

Re: [PATCH v2 1/3] spi: Introduce one new field to set word delay

[Jan Kundrát]

On čtvrtek 16. srpna 2018 14:54:49 CEST, Baolin Wang wrote:
> + * @word_delay: clock cycles to inter word delay after each word size
> + *	(set by bits_per_word) transmission.

I need a similar functionality for talking to a SPI device from userspace  
-- see my attempt for implementing this in spi-orion.c at [1]. The device's 
datasheet says that I should wait, e.g., 3µs between each two words. I 
therefore like this patch :).

The description can be improved because it left me wondering what "clock 
this is about. I suppose it's about the SPI clock cycles and not CPU clock 
cycles, right? I'll be hapy to patch this once Baolin confirms that that is 
the intended meaning.

It seems that this is only implemented in one newly added driver. I'm 
interested in supporting this in spi-orion.c, but that sounds like 
driver-specific work for something which is pretty generic. How should this 
be implemented? Given that drivers for SPI masters can implement a function 
which transfers several words at once, there are not that many better 
possibilities than adding udelay()s, though. Thoughts?

What is your plan to do with drivers which do not implement this (yet)? If 
a spi_transfer gets queued which asks for a word_delay delay, it is 
silently ignored now, AFAIU.

What about userspace support, spidev and spi_ioc_transfer (that's my 
target, actually)? Is it OK to s/pad/word_delay/ in the spidev code and 
pass that to the generated struct spi_transfer? In my opinion, once we 
support specifying this from userspace, one has to definitely check that 
the SPI controller is ready to honor this request. Do we want a new bit in 
spi_controller.flags for this?

With kind regards,
Jan

[1] https://patchwork.kernel.org/patch/10221397/

Re: [PATCH v2 1/3] spi: Introduce one new field to set word delay

[Mark Brown]

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On Wed, Aug 29, 2018 at 01:33:24PM +0200, Jan Kundrát wrote:
> On čtvrtek 16. srpna 2018 14:54:49 CEST, Baolin Wang wrote:
> > + * @word_delay: clock cycles to inter word delay after each word size
> > + *	(set by bits_per_word) transmission.

> The description can be improved because it left me wondering what "clock
> this is about. I suppose it's about the SPI clock cycles and not CPU clock
> cycles, right? I'll be hapy to patch this once Baolin confirms that that is
> the intended meaning.

That's certainly how I read it.

> It seems that this is only implemented in one newly added driver. I'm
> interested in supporting this in spi-orion.c, but that sounds like
> driver-specific work for something which is pretty generic. How should this
> be implemented? Given that drivers for SPI masters can implement a function
> which transfers several words at once, there are not that many better
> possibilities than adding udelay()s, though. Thoughts?

Yeah, you'd need to split the transfer into words and then add a delay
between which would be rather expensive but it's about as good as we can
get I think.

> What is your plan to do with drivers which do not implement this (yet)? If a
> spi_transfer gets queued which asks for a word_delay delay, it is silently
> ignored now, AFAIU.

Yes.  A generic handler would be best.

> What about userspace support, spidev and spi_ioc_transfer (that's my target,
> actually)? Is it OK to s/pad/word_delay/ in the spidev code and pass that to
> the generated struct spi_transfer? In my opinion, once we support specifying
> this from userspace, one has to definitely check that the SPI controller is
> ready to honor this request. Do we want a new bit in spi_controller.flags
> for this?

Not seeing pad in the spidev code?  A feature flag would make sense along
with a generic implementation.

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Re: [PATCH v2 1/3] spi: Introduce one new field to set word delay

[Baolin Wang]

On 29 August 2018 at 19:33, Jan Kundrát <jan.kundrat@cesnet.cz> wrote:
> On čtvrtek 16. srpna 2018 14:54:49 CEST, Baolin Wang wrote:
>>
>> + * @word_delay: clock cycles to inter word delay after each word size
>> + *     (set by bits_per_word) transmission.
>
>
> I need a similar functionality for talking to a SPI device from userspace
> -- see my attempt for implementing this in spi-orion.c at [1]. The device's
> datasheet says that I should wait, e.g., 3µs between each two words. I
> therefore like this patch :).
>
> The description can be improved because it left me wondering what "clock
> this is about. I suppose it's about the SPI clock cycles and not CPU clock
> cycles, right? I'll be hapy to patch this once Baolin confirms that that is
> the intended meaning.

Sorry for confusing. Since our SPI word delay unit is clock cycle of
the SPI clock, so my intention of the word_delay's unit is SPI clock
cycles according to our previous discussion.

>
> It seems that this is only implemented in one newly added driver. I'm
> interested in supporting this in spi-orion.c, but that sounds like
> driver-specific work for something which is pretty generic. How should this
> be implemented? Given that drivers for SPI masters can implement a function
> which transfers several words at once, there are not that many better
> possibilities than adding udelay()s, though. Thoughts?
>
> What is your plan to do with drivers which do not implement this (yet)? If a
> spi_transfer gets queued which asks for a word_delay delay, it is silently
> ignored now, AFAIU.
>
> What about userspace support, spidev and spi_ioc_transfer (that's my target,
> actually)? Is it OK to s/pad/word_delay/ in the spidev code and pass that to
> the generated struct spi_transfer? In my opinion, once we support specifying
> this from userspace, one has to definitely check that the SPI controller is
> ready to honor this request. Do we want a new bit in spi_controller.flags
> for this?
>
> With kind regards,
> Jan
>
> [1] https://patchwork.kernel.org/patch/10221397/



-- 
Baolin Wang
Best Regards