[Patch V3 1/2] spi: imx: add devicetree binding for lpspi

[Patch V3 1/2] spi: imx: add devicetree binding for lpspi

[Gao Pan]

Add a binding document for lpspi driver

Signed-off-by: Gao Pan <pandy.gao-3arQi8VN3Tc@public.gmane.org>
---
 .../devicetree/bindings/spi/spi-fsl-lpspi.txt         | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.txt b/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.txt
new file mode 100644
index 0000000..225ace1
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.txt
@@ -0,0 +1,19 @@
+* Freescale Low Power SPI (LPSPI) for i.MX
+
+Required properties:
+- compatible :
+  - "fsl,imx7ulp-spi" for LPSPI compatible with the one integrated on i.MX7ULP soc
+- reg : address and length of the lpspi master registers
+- interrupt-parent : core interrupt controller
+- interrupts : lpspi interrupt
+- clocks : lpspi clock specifier
+
+Examples:
+
+lpspi2: lpspi@40290000 {
+	compatible = "fsl,imx7ulp-spi";
+	reg = <0x40290000 0x10000>;
+	interrupt-parent = <&intc>;
+	interrupts = <GIC_SPI 28 IRQ_TYPE_LEVEL_HIGH>;
+	clocks = <&clks IMX7ULP_CLK_LPSPI2>;
+};
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Patch V3 2/2] spi: imx: add lpspi bus driver

[Gao Pan]

This patch adds lpspi driver to support new i.MX products which use
lpspi instead of ecspi.

The lpspi can continue operating in stop mode when an appropriate
clock is available. It is also designed for low CPU overhead with
DMA offloading of FIFO register accesses.

Signed-off-by: Gao Pan <pandy.gao-3arQi8VN3Tc@public.gmane.org>
Reviewed-by: Fugang Duan <B38611-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
---
V2:
 -use normal spi interface rather than bitbang

V3:
 -remove unnecessary message check
 -use clk_prepare_enable() infsl_lpspi_prepare_message()
 -add necessary comments
 -remove doing linearization into a single buffer

 drivers/spi/Kconfig         |   6 +
 drivers/spi/Makefile        |   1 +
 drivers/spi/spi-fsl-lpspi.c | 512 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 519 insertions(+)

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 6891091..ccce8fe 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -264,6 +264,12 @@ config SPI_FALCON
 	  has only been tested with m25p80 type chips. The hardware has no
 	  support for other types of SPI peripherals.
 
+config SPI_FSL_LPSPI
+	tristate "Freescale i.MX LPSPI controller"
+	depends on ARCH_MXC || COMPILE_TEST
+	help
+	  This enables Freescale i.MX LPSPI controllers in master mode.
+
 config SPI_GPIO
 	tristate "GPIO-based bitbanging SPI Master"
 	depends on GPIOLIB || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index aa939d9..1e890d9 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_SPI_FSL_CPM)		+= spi-fsl-cpm.o
 obj-$(CONFIG_SPI_FSL_DSPI)		+= spi-fsl-dspi.o
 obj-$(CONFIG_SPI_FSL_LIB)		+= spi-fsl-lib.o
 obj-$(CONFIG_SPI_FSL_ESPI)		+= spi-fsl-espi.o
+obj-$(CONFIG_SPI_FSL_LPSPI)		+= spi-fsl-lpspi.o
 obj-$(CONFIG_SPI_FSL_SPI)		+= spi-fsl-spi.o
 obj-$(CONFIG_SPI_GPIO)			+= spi-gpio.o
 obj-$(CONFIG_SPI_IMG_SPFI)		+= spi-img-spfi.o
diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
new file mode 100644
index 0000000..bcb7b28
--- /dev/null
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -0,0 +1,512 @@
+/*
+ * Freescale i.MX7ULP LPSPI driver
+ *
+ * Copyright 2016 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.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/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/types.h>
+
+#define DRIVER_NAME "fsl_lpspi"
+
+/* i.MX7ULP LPSPI registers */
+#define IMX7ULP_VERID	0x0
+#define IMX7ULP_PARAM	0x4
+#define IMX7ULP_CR	0x10
+#define IMX7ULP_SR	0x14
+#define IMX7ULP_IER	0x18
+#define IMX7ULP_DER	0x1c
+#define IMX7ULP_CFGR0	0x20
+#define IMX7ULP_CFGR1	0x24
+#define IMX7ULP_DMR0	0x30
+#define IMX7ULP_DMR1	0x34
+#define IMX7ULP_CCR	0x40
+#define IMX7ULP_FCR	0x58
+#define IMX7ULP_FSR	0x5c
+#define IMX7ULP_TCR	0x60
+#define IMX7ULP_TDR	0x64
+#define IMX7ULP_RSR	0x70
+#define IMX7ULP_RDR	0x74
+
+/* General control register field define */
+#define CR_RRF		BIT(9)
+#define CR_RTF		BIT(8)
+#define CR_RST		BIT(1)
+#define CR_MEN		BIT(0)
+#define SR_TCF		BIT(10)
+#define SR_RDF		BIT(1)
+#define SR_TDF		BIT(0)
+#define IER_TCIE	BIT(10)
+#define IER_RDIE	BIT(1)
+#define IER_TDIE	BIT(0)
+#define CFGR1_PCSCFG	BIT(27)
+#define CFGR1_PCSPOL	BIT(8)
+#define CFGR1_NOSTALL	BIT(3)
+#define CFGR1_MASTER	BIT(0)
+#define RSR_RXEMPTY	BIT(1)
+#define TCR_CPOL	BIT(31)
+#define TCR_CPHA	BIT(30)
+#define TCR_CONT	BIT(21)
+#define TCR_CONTC	BIT(20)
+#define TCR_RXMSK	BIT(19)
+#define TCR_TXMSK	BIT(18)
+
+static int clkdivs[] = {1, 2, 4, 8, 16, 32, 64, 128};
+
+struct lpspi_config {
+	u8 bpw;
+	u8 chip_select;
+	u8 prescale;
+	u16 mode;
+	u32 speed_hz;
+};
+
+struct fsl_lpspi_data {
+	struct device *dev;
+	void __iomem *base;
+	struct clk *clk;
+
+	void *rx_buf;
+	const void *tx_buf;
+	void (*tx)(struct fsl_lpspi_data *);
+	void (*rx)(struct fsl_lpspi_data *);
+
+	u32 remain;
+	u8 txfifosize;
+	u8 rxfifosize;
+
+	struct lpspi_config config;
+	struct completion xfer_done;
+};
+
+static const struct of_device_id fsl_lpspi_dt_ids[] = {
+	{ .compatible = "fsl,imx7ulp-spi", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, fsl_lpspi_dt_ids);
+
+#define LPSPI_BUF_RX(type)						\
+static void fsl_lpspi_buf_rx_##type(struct fsl_lpspi_data *fsl_lpspi)	\
+{									\
+	unsigned int val = readl(fsl_lpspi->base + IMX7ULP_RDR);	\
+									\
+	if (fsl_lpspi->rx_buf) {					\
+		*(type *)fsl_lpspi->rx_buf = val;			\
+		fsl_lpspi->rx_buf += sizeof(type);                      \
+	}								\
+}
+
+#define LPSPI_BUF_TX(type)						\
+static void fsl_lpspi_buf_tx_##type(struct fsl_lpspi_data *fsl_lpspi)	\
+{									\
+	type val = 0;							\
+									\
+	if (fsl_lpspi->tx_buf) {					\
+		val = *(type *)fsl_lpspi->tx_buf;			\
+		fsl_lpspi->tx_buf += sizeof(type);			\
+	}								\
+									\
+	fsl_lpspi->remain -= sizeof(type);				\
+	writel(val, fsl_lpspi->base + IMX7ULP_TDR);			\
+}
+
+LPSPI_BUF_RX(u8)
+LPSPI_BUF_TX(u8)
+LPSPI_BUF_RX(u16)
+LPSPI_BUF_TX(u16)
+LPSPI_BUF_RX(u32)
+LPSPI_BUF_TX(u32)
+
+static void fsl_lpspi_intctrl(struct fsl_lpspi_data *fsl_lpspi,
+			      unsigned int enable)
+{
+	writel(enable, fsl_lpspi->base + IMX7ULP_IER);
+}
+
+static int fsl_lpspi_prepare_message(struct spi_master *master,
+				     struct spi_message *msg)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+	return clk_prepare_enable(fsl_lpspi->clk);
+}
+
+static int
+fsl_lpspi_unprepare_message(struct spi_master *master, struct spi_message *msg)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+	clk_disable_unprepare(fsl_lpspi->clk);
+
+	return 0;
+}
+
+static int fsl_lpspi_txfifo_empty(struct fsl_lpspi_data *fsl_lpspi)
+{
+	u32 txcnt;
+	unsigned long orig_jiffies = jiffies;
+
+	do {
+		txcnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
+
+		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
+			dev_dbg(fsl_lpspi->dev, "txfifo empty timeout\n");
+			return -ETIMEDOUT;
+		}
+		schedule();
+
+	} while (txcnt);
+
+	return 0;
+}
+
+static void fsl_lpspi_write_tx_fifo(struct fsl_lpspi_data *fsl_lpspi)
+{
+	u8 txfifo_cnt;
+
+	txfifo_cnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
+
+	while (txfifo_cnt < fsl_lpspi->txfifosize) {
+		if (!fsl_lpspi->remain)
+			break;
+		fsl_lpspi->tx(fsl_lpspi);
+		txfifo_cnt++;
+	}
+
+	if (!fsl_lpspi->remain && (txfifo_cnt < fsl_lpspi->txfifosize))
+		writel(0, fsl_lpspi->base + IMX7ULP_TDR);
+	else
+		fsl_lpspi_intctrl(fsl_lpspi, IER_TDIE);
+}
+
+static void fsl_lpspi_read_rx_fifo(struct fsl_lpspi_data *fsl_lpspi)
+{
+	while (!(readl(fsl_lpspi->base + IMX7ULP_RSR) & RSR_RXEMPTY))
+		fsl_lpspi->rx(fsl_lpspi);
+}
+
+static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi,
+			      bool is_first_xfer)
+{
+	u32 temp = 0;
+
+	temp |= fsl_lpspi->config.bpw - 1;
+	temp |= fsl_lpspi->config.prescale << 27;
+	temp |= (fsl_lpspi->config.mode & 0x11) << 30;
+	temp |= (fsl_lpspi->config.chip_select & 0x3) << 24;
+
+	/*
+	 * Set TCR_CONT will keep SS asserted after current transfer.
+	 * For the first transfer, clear TCR_CONTC to assert SS.
+	 * For subsequent transfer, set TCR_CONTC to keep SS asserted.
+	 */
+	temp |= TCR_CONT;
+	if (is_first_xfer)
+		temp &= ~TCR_CONTC;
+	else
+		temp |= TCR_CONTC;
+
+	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
+
+	dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
+}
+
+static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
+{
+	u8 txwatermark, rxwatermark;
+	u32 temp;
+
+	temp = readl(fsl_lpspi->base + IMX7ULP_PARAM);
+	fsl_lpspi->txfifosize = 1 << (temp & 0x0f);
+	fsl_lpspi->rxfifosize = 1 << ((temp >> 8) & 0x0f);
+	rxwatermark = fsl_lpspi->txfifosize >> 1;
+	txwatermark = fsl_lpspi->rxfifosize >> 1;
+	temp = txwatermark | rxwatermark << 16;
+
+	writel(temp, fsl_lpspi->base + IMX7ULP_FCR);
+
+	dev_dbg(fsl_lpspi->dev, "FCR=0x%x\n", temp);
+}
+
+static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
+{
+	struct lpspi_config config = fsl_lpspi->config;
+	unsigned int perclk_rate, scldiv;
+	u8 prescale;
+
+	perclk_rate = clk_get_rate(fsl_lpspi->clk);
+	for (prescale = 0; prescale < 8; prescale++) {
+		scldiv = perclk_rate /
+			 (clkdivs[prescale] * config.speed_hz) - 2;
+		if (scldiv < 256) {
+			fsl_lpspi->config.prescale = prescale;
+			break;
+		}
+	}
+
+	if (prescale == 8 && scldiv >= 256)
+		return -EINVAL;
+
+	writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);
+
+	dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, scldiv=%d\n",
+		perclk_rate, config.speed_hz, prescale, scldiv);
+
+	return 0;
+}
+
+static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
+{
+	u32 temp;
+	int ret;
+
+	temp = CR_RST;
+	writel(temp, fsl_lpspi->base + IMX7ULP_CR);
+	writel(0, fsl_lpspi->base + IMX7ULP_CR);
+
+	ret = fsl_lpspi_set_bitrate(fsl_lpspi);
+	if (ret)
+		return ret;
+
+	fsl_lpspi_set_watermark(fsl_lpspi);
+
+	temp = CFGR1_PCSCFG | CFGR1_MASTER | CFGR1_NOSTALL;
+	if (fsl_lpspi->config.mode & SPI_CS_HIGH)
+		temp |= CFGR1_PCSPOL;
+	writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);
+
+	temp = readl(fsl_lpspi->base + IMX7ULP_CR);
+	temp |= CR_RRF | CR_RTF | CR_MEN;
+	writel(temp, fsl_lpspi->base + IMX7ULP_CR);
+
+	return 0;
+}
+
+static void fsl_lpspi_setup_transfer(struct spi_device *spi,
+				     struct spi_transfer *t)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(spi->master);
+
+	fsl_lpspi->config.mode = spi->mode;
+	fsl_lpspi->config.bpw = t ? t->bits_per_word : spi->bits_per_word;
+	fsl_lpspi->config.speed_hz = t ? t->speed_hz : spi->max_speed_hz;
+	fsl_lpspi->config.chip_select = spi->chip_select;
+
+	if (!fsl_lpspi->config.speed_hz)
+		fsl_lpspi->config.speed_hz = spi->max_speed_hz;
+	if (!fsl_lpspi->config.bpw)
+		fsl_lpspi->config.bpw = spi->bits_per_word;
+
+	/* Initialize the functions for transfer */
+	if (fsl_lpspi->config.bpw <= 8) {
+		fsl_lpspi->rx = fsl_lpspi_buf_rx_u8;
+		fsl_lpspi->tx = fsl_lpspi_buf_tx_u8;
+	} else if (fsl_lpspi->config.bpw <= 16) {
+		fsl_lpspi->rx = fsl_lpspi_buf_rx_u16;
+		fsl_lpspi->tx = fsl_lpspi_buf_tx_u16;
+	} else {
+		fsl_lpspi->rx = fsl_lpspi_buf_rx_u32;
+		fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
+	}
+
+	fsl_lpspi_config(fsl_lpspi);
+}
+
+static int fsl_lpspi_transfer_one(struct spi_master *master,
+				  struct spi_device *spi,
+				  struct spi_transfer *t)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+	int ret;
+
+	fsl_lpspi->tx_buf = t->tx_buf;
+	fsl_lpspi->rx_buf = t->rx_buf;
+	fsl_lpspi->remain = t->len;
+
+	reinit_completion(&fsl_lpspi->xfer_done);
+	fsl_lpspi_write_tx_fifo(fsl_lpspi);
+	wait_for_completion(&fsl_lpspi->xfer_done);
+
+	ret = fsl_lpspi_txfifo_empty(fsl_lpspi);
+	fsl_lpspi_read_rx_fifo(fsl_lpspi);
+
+	return ret;
+}
+
+static int fsl_lpspi_transfer_one_msg(struct spi_master *master,
+				      struct spi_message *msg)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+	struct spi_device *spi = msg->spi;
+	struct spi_transfer *xfer;
+	bool is_first_xfer = true;
+	u32 temp;
+	int ret;
+
+	msg->status = 0;
+	msg->actual_length = 0;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		fsl_lpspi_setup_transfer(spi, xfer);
+		fsl_lpspi_set_cmd(fsl_lpspi, is_first_xfer);
+
+		is_first_xfer = false;
+
+		ret = fsl_lpspi_transfer_one(master, spi, xfer);
+		if (ret < 0)
+			goto complete;
+
+		msg->actual_length += xfer->len;
+	}
+
+complete:
+	/* de-assert SS, then finalize current message */
+	temp = readl(fsl_lpspi->base + IMX7ULP_TCR);
+	temp &= ~TCR_CONTC;
+	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
+
+	msg->status = ret;
+	spi_finalize_current_message(master);
+
+	return ret;
+}
+
+static irqreturn_t fsl_lpspi_isr(int irq, void *dev_id)
+{
+	struct fsl_lpspi_data *fsl_lpspi = dev_id;
+	u32 temp;
+
+	fsl_lpspi_intctrl(fsl_lpspi, 0);
+	temp = readl(fsl_lpspi->base + IMX7ULP_SR);
+
+	fsl_lpspi_read_rx_fifo(fsl_lpspi);
+
+	if (temp & SR_TDF) {
+		fsl_lpspi_write_tx_fifo(fsl_lpspi);
+
+		if (!fsl_lpspi->remain)
+			complete(&fsl_lpspi->xfer_done);
+
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static int fsl_lpspi_probe(struct platform_device *pdev)
+{
+	struct fsl_lpspi_data *fsl_lpspi;
+	struct spi_master *master;
+	struct resource *res;
+	int ret, irq;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct fsl_lpspi_data));
+	if (!master)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, master);
+
+	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
+	master->bus_num = pdev->id;
+
+	fsl_lpspi = spi_master_get_devdata(master);
+	fsl_lpspi->dev = &pdev->dev;
+
+	master->transfer_one_message = fsl_lpspi_transfer_one_msg;
+	master->prepare_message = fsl_lpspi_prepare_message;
+	master->unprepare_message = fsl_lpspi_unprepare_message;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
+	master->dev.of_node = pdev->dev.of_node;
+	master->bus_num = pdev->id;
+
+	init_completion(&fsl_lpspi->xfer_done);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	fsl_lpspi->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(fsl_lpspi->base)) {
+		ret = PTR_ERR(fsl_lpspi->base);
+		goto out_master_put;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		ret = irq;
+		goto out_master_put;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, fsl_lpspi_isr, 0,
+			       dev_name(&pdev->dev), fsl_lpspi);
+	if (ret) {
+		dev_err(&pdev->dev, "can't get irq%d: %d\n", irq, ret);
+		goto out_master_put;
+	}
+
+	fsl_lpspi->clk = devm_clk_get(&pdev->dev, "ipg");
+	if (IS_ERR(fsl_lpspi->clk)) {
+		ret = PTR_ERR(fsl_lpspi->clk);
+		goto out_master_put;
+	}
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "spi_register_master error.\n");
+		goto out_master_put;
+	}
+
+	return 0;
+
+out_master_put:
+	spi_master_put(master);
+
+	return ret;
+}
+
+static int fsl_lpspi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+	clk_disable_unprepare(fsl_lpspi->clk);
+
+	return 0;
+}
+
+static struct platform_driver fsl_lpspi_driver = {
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .of_match_table = fsl_lpspi_dt_ids,
+		   },
+	.probe = fsl_lpspi_probe,
+	.remove = fsl_lpspi_remove,
+};
+module_platform_driver(fsl_lpspi_driver);
+
+MODULE_DESCRIPTION("LPSPI Master Controller driver");
+MODULE_AUTHOR("Gao Pan <pandy.gao-3arQi8VN3Tc@public.gmane.org>");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [Patch V3 2/2] spi: imx: add lpspi bus driver

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 1280 bytes --]

On Tue, Nov 22, 2016 at 09:52:17PM +0800, Gao Pan wrote:
> This patch adds lpspi driver to support new i.MX products which use
> lpspi instead of ecspi.

I'll apply this but there's some small issues, can you please fix them
up with incremental patches:

> +static int fsl_lpspi_prepare_message(struct spi_master *master,
> +				     struct spi_message *msg)
> +{
> +	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
> +
> +	return clk_prepare_enable(fsl_lpspi->clk);
> +}

Rather than doing this per message it's a bit better to do it in
prepare_transfer_hardware(), that way if there's a sequence of messages
queued one after another we don't turn the clock on and off all the
time.  In practice it's likely to make a negligable difference to
performance but it's just better practice.

> +static int fsl_lpspi_txfifo_empty(struct fsl_lpspi_data *fsl_lpspi)
> +{
> +	u32 txcnt;
> +	unsigned long orig_jiffies = jiffies;
> +
> +	do {
> +		txcnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
> +
> +		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
> +			dev_dbg(fsl_lpspi->dev, "txfifo empty timeout\n");
> +			return -ETIMEDOUT;
> +		}
> +		schedule();

Call cond_resched() instead, it has the effect you're looking for in a
more modern way.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 455 bytes --]

Applied "spi: imx: add lpspi bus driver" to the spi tree

[Mark Brown]

The patch

   spi: imx: add lpspi bus driver

has been applied to the spi tree at

   git://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 5314987de5e5f5e38436ef4a69328bc472bbd63e Mon Sep 17 00:00:00 2001
From: Gao Pan <pandy.gao-3arQi8VN3Tc@public.gmane.org>
Date: Tue, 22 Nov 2016 21:52:17 +0800
Subject: [PATCH] spi: imx: add lpspi bus driver

This patch adds lpspi driver to support new i.MX products which use
lpspi instead of ecspi.

The lpspi can continue operating in stop mode when an appropriate
clock is available. It is also designed for low CPU overhead with
DMA offloading of FIFO register accesses.

Signed-off-by: Gao Pan <pandy.gao-3arQi8VN3Tc@public.gmane.org>
Reviewed-by: Fugang Duan <B38611-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
Signed-off-by: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 drivers/spi/Kconfig         |   6 +
 drivers/spi/Makefile        |   1 +
 drivers/spi/spi-fsl-lpspi.c | 512 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 519 insertions(+)
 create mode 100644 drivers/spi/spi-fsl-lpspi.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index b7995474148c..91ae18035b6b 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -264,6 +264,12 @@ config SPI_FALCON
 	  has only been tested with m25p80 type chips. The hardware has no
 	  support for other types of SPI peripherals.
 
+config SPI_FSL_LPSPI
+	tristate "Freescale i.MX LPSPI controller"
+	depends on ARCH_MXC || COMPILE_TEST
+	help
+	  This enables Freescale i.MX LPSPI controllers in master mode.
+
 config SPI_GPIO
 	tristate "GPIO-based bitbanging SPI Master"
 	depends on GPIOLIB || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index aa939d955521..1e890d98db7a 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_SPI_FSL_CPM)		+= spi-fsl-cpm.o
 obj-$(CONFIG_SPI_FSL_DSPI)		+= spi-fsl-dspi.o
 obj-$(CONFIG_SPI_FSL_LIB)		+= spi-fsl-lib.o
 obj-$(CONFIG_SPI_FSL_ESPI)		+= spi-fsl-espi.o
+obj-$(CONFIG_SPI_FSL_LPSPI)		+= spi-fsl-lpspi.o
 obj-$(CONFIG_SPI_FSL_SPI)		+= spi-fsl-spi.o
 obj-$(CONFIG_SPI_GPIO)			+= spi-gpio.o
 obj-$(CONFIG_SPI_IMG_SPFI)		+= spi-img-spfi.o
diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
new file mode 100644
index 000000000000..bcb7b284d2f2
--- /dev/null
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -0,0 +1,512 @@
+/*
+ * Freescale i.MX7ULP LPSPI driver
+ *
+ * Copyright 2016 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.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/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/types.h>
+
+#define DRIVER_NAME "fsl_lpspi"
+
+/* i.MX7ULP LPSPI registers */
+#define IMX7ULP_VERID	0x0
+#define IMX7ULP_PARAM	0x4
+#define IMX7ULP_CR	0x10
+#define IMX7ULP_SR	0x14
+#define IMX7ULP_IER	0x18
+#define IMX7ULP_DER	0x1c
+#define IMX7ULP_CFGR0	0x20
+#define IMX7ULP_CFGR1	0x24
+#define IMX7ULP_DMR0	0x30
+#define IMX7ULP_DMR1	0x34
+#define IMX7ULP_CCR	0x40
+#define IMX7ULP_FCR	0x58
+#define IMX7ULP_FSR	0x5c
+#define IMX7ULP_TCR	0x60
+#define IMX7ULP_TDR	0x64
+#define IMX7ULP_RSR	0x70
+#define IMX7ULP_RDR	0x74
+
+/* General control register field define */
+#define CR_RRF		BIT(9)
+#define CR_RTF		BIT(8)
+#define CR_RST		BIT(1)
+#define CR_MEN		BIT(0)
+#define SR_TCF		BIT(10)
+#define SR_RDF		BIT(1)
+#define SR_TDF		BIT(0)
+#define IER_TCIE	BIT(10)
+#define IER_RDIE	BIT(1)
+#define IER_TDIE	BIT(0)
+#define CFGR1_PCSCFG	BIT(27)
+#define CFGR1_PCSPOL	BIT(8)
+#define CFGR1_NOSTALL	BIT(3)
+#define CFGR1_MASTER	BIT(0)
+#define RSR_RXEMPTY	BIT(1)
+#define TCR_CPOL	BIT(31)
+#define TCR_CPHA	BIT(30)
+#define TCR_CONT	BIT(21)
+#define TCR_CONTC	BIT(20)
+#define TCR_RXMSK	BIT(19)
+#define TCR_TXMSK	BIT(18)
+
+static int clkdivs[] = {1, 2, 4, 8, 16, 32, 64, 128};
+
+struct lpspi_config {
+	u8 bpw;
+	u8 chip_select;
+	u8 prescale;
+	u16 mode;
+	u32 speed_hz;
+};
+
+struct fsl_lpspi_data {
+	struct device *dev;
+	void __iomem *base;
+	struct clk *clk;
+
+	void *rx_buf;
+	const void *tx_buf;
+	void (*tx)(struct fsl_lpspi_data *);
+	void (*rx)(struct fsl_lpspi_data *);
+
+	u32 remain;
+	u8 txfifosize;
+	u8 rxfifosize;
+
+	struct lpspi_config config;
+	struct completion xfer_done;
+};
+
+static const struct of_device_id fsl_lpspi_dt_ids[] = {
+	{ .compatible = "fsl,imx7ulp-spi", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, fsl_lpspi_dt_ids);
+
+#define LPSPI_BUF_RX(type)						\
+static void fsl_lpspi_buf_rx_##type(struct fsl_lpspi_data *fsl_lpspi)	\
+{									\
+	unsigned int val = readl(fsl_lpspi->base + IMX7ULP_RDR);	\
+									\
+	if (fsl_lpspi->rx_buf) {					\
+		*(type *)fsl_lpspi->rx_buf = val;			\
+		fsl_lpspi->rx_buf += sizeof(type);                      \
+	}								\
+}
+
+#define LPSPI_BUF_TX(type)						\
+static void fsl_lpspi_buf_tx_##type(struct fsl_lpspi_data *fsl_lpspi)	\
+{									\
+	type val = 0;							\
+									\
+	if (fsl_lpspi->tx_buf) {					\
+		val = *(type *)fsl_lpspi->tx_buf;			\
+		fsl_lpspi->tx_buf += sizeof(type);			\
+	}								\
+									\
+	fsl_lpspi->remain -= sizeof(type);				\
+	writel(val, fsl_lpspi->base + IMX7ULP_TDR);			\
+}
+
+LPSPI_BUF_RX(u8)
+LPSPI_BUF_TX(u8)
+LPSPI_BUF_RX(u16)
+LPSPI_BUF_TX(u16)
+LPSPI_BUF_RX(u32)
+LPSPI_BUF_TX(u32)
+
+static void fsl_lpspi_intctrl(struct fsl_lpspi_data *fsl_lpspi,
+			      unsigned int enable)
+{
+	writel(enable, fsl_lpspi->base + IMX7ULP_IER);
+}
+
+static int fsl_lpspi_prepare_message(struct spi_master *master,
+				     struct spi_message *msg)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+	return clk_prepare_enable(fsl_lpspi->clk);
+}
+
+static int
+fsl_lpspi_unprepare_message(struct spi_master *master, struct spi_message *msg)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+	clk_disable_unprepare(fsl_lpspi->clk);
+
+	return 0;
+}
+
+static int fsl_lpspi_txfifo_empty(struct fsl_lpspi_data *fsl_lpspi)
+{
+	u32 txcnt;
+	unsigned long orig_jiffies = jiffies;
+
+	do {
+		txcnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
+
+		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
+			dev_dbg(fsl_lpspi->dev, "txfifo empty timeout\n");
+			return -ETIMEDOUT;
+		}
+		schedule();
+
+	} while (txcnt);
+
+	return 0;
+}
+
+static void fsl_lpspi_write_tx_fifo(struct fsl_lpspi_data *fsl_lpspi)
+{
+	u8 txfifo_cnt;
+
+	txfifo_cnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
+
+	while (txfifo_cnt < fsl_lpspi->txfifosize) {
+		if (!fsl_lpspi->remain)
+			break;
+		fsl_lpspi->tx(fsl_lpspi);
+		txfifo_cnt++;
+	}
+
+	if (!fsl_lpspi->remain && (txfifo_cnt < fsl_lpspi->txfifosize))
+		writel(0, fsl_lpspi->base + IMX7ULP_TDR);
+	else
+		fsl_lpspi_intctrl(fsl_lpspi, IER_TDIE);
+}
+
+static void fsl_lpspi_read_rx_fifo(struct fsl_lpspi_data *fsl_lpspi)
+{
+	while (!(readl(fsl_lpspi->base + IMX7ULP_RSR) & RSR_RXEMPTY))
+		fsl_lpspi->rx(fsl_lpspi);
+}
+
+static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi,
+			      bool is_first_xfer)
+{
+	u32 temp = 0;
+
+	temp |= fsl_lpspi->config.bpw - 1;
+	temp |= fsl_lpspi->config.prescale << 27;
+	temp |= (fsl_lpspi->config.mode & 0x11) << 30;
+	temp |= (fsl_lpspi->config.chip_select & 0x3) << 24;
+
+	/*
+	 * Set TCR_CONT will keep SS asserted after current transfer.
+	 * For the first transfer, clear TCR_CONTC to assert SS.
+	 * For subsequent transfer, set TCR_CONTC to keep SS asserted.
+	 */
+	temp |= TCR_CONT;
+	if (is_first_xfer)
+		temp &= ~TCR_CONTC;
+	else
+		temp |= TCR_CONTC;
+
+	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
+
+	dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
+}
+
+static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
+{
+	u8 txwatermark, rxwatermark;
+	u32 temp;
+
+	temp = readl(fsl_lpspi->base + IMX7ULP_PARAM);
+	fsl_lpspi->txfifosize = 1 << (temp & 0x0f);
+	fsl_lpspi->rxfifosize = 1 << ((temp >> 8) & 0x0f);
+	rxwatermark = fsl_lpspi->txfifosize >> 1;
+	txwatermark = fsl_lpspi->rxfifosize >> 1;
+	temp = txwatermark | rxwatermark << 16;
+
+	writel(temp, fsl_lpspi->base + IMX7ULP_FCR);
+
+	dev_dbg(fsl_lpspi->dev, "FCR=0x%x\n", temp);
+}
+
+static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
+{
+	struct lpspi_config config = fsl_lpspi->config;
+	unsigned int perclk_rate, scldiv;
+	u8 prescale;
+
+	perclk_rate = clk_get_rate(fsl_lpspi->clk);
+	for (prescale = 0; prescale < 8; prescale++) {
+		scldiv = perclk_rate /
+			 (clkdivs[prescale] * config.speed_hz) - 2;
+		if (scldiv < 256) {
+			fsl_lpspi->config.prescale = prescale;
+			break;
+		}
+	}
+
+	if (prescale == 8 && scldiv >= 256)
+		return -EINVAL;
+
+	writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);
+
+	dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, scldiv=%d\n",
+		perclk_rate, config.speed_hz, prescale, scldiv);
+
+	return 0;
+}
+
+static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
+{
+	u32 temp;
+	int ret;
+
+	temp = CR_RST;
+	writel(temp, fsl_lpspi->base + IMX7ULP_CR);
+	writel(0, fsl_lpspi->base + IMX7ULP_CR);
+
+	ret = fsl_lpspi_set_bitrate(fsl_lpspi);
+	if (ret)
+		return ret;
+
+	fsl_lpspi_set_watermark(fsl_lpspi);
+
+	temp = CFGR1_PCSCFG | CFGR1_MASTER | CFGR1_NOSTALL;
+	if (fsl_lpspi->config.mode & SPI_CS_HIGH)
+		temp |= CFGR1_PCSPOL;
+	writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);
+
+	temp = readl(fsl_lpspi->base + IMX7ULP_CR);
+	temp |= CR_RRF | CR_RTF | CR_MEN;
+	writel(temp, fsl_lpspi->base + IMX7ULP_CR);
+
+	return 0;
+}
+
+static void fsl_lpspi_setup_transfer(struct spi_device *spi,
+				     struct spi_transfer *t)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(spi->master);
+
+	fsl_lpspi->config.mode = spi->mode;
+	fsl_lpspi->config.bpw = t ? t->bits_per_word : spi->bits_per_word;
+	fsl_lpspi->config.speed_hz = t ? t->speed_hz : spi->max_speed_hz;
+	fsl_lpspi->config.chip_select = spi->chip_select;
+
+	if (!fsl_lpspi->config.speed_hz)
+		fsl_lpspi->config.speed_hz = spi->max_speed_hz;
+	if (!fsl_lpspi->config.bpw)
+		fsl_lpspi->config.bpw = spi->bits_per_word;
+
+	/* Initialize the functions for transfer */
+	if (fsl_lpspi->config.bpw <= 8) {
+		fsl_lpspi->rx = fsl_lpspi_buf_rx_u8;
+		fsl_lpspi->tx = fsl_lpspi_buf_tx_u8;
+	} else if (fsl_lpspi->config.bpw <= 16) {
+		fsl_lpspi->rx = fsl_lpspi_buf_rx_u16;
+		fsl_lpspi->tx = fsl_lpspi_buf_tx_u16;
+	} else {
+		fsl_lpspi->rx = fsl_lpspi_buf_rx_u32;
+		fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
+	}
+
+	fsl_lpspi_config(fsl_lpspi);
+}
+
+static int fsl_lpspi_transfer_one(struct spi_master *master,
+				  struct spi_device *spi,
+				  struct spi_transfer *t)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+	int ret;
+
+	fsl_lpspi->tx_buf = t->tx_buf;
+	fsl_lpspi->rx_buf = t->rx_buf;
+	fsl_lpspi->remain = t->len;
+
+	reinit_completion(&fsl_lpspi->xfer_done);
+	fsl_lpspi_write_tx_fifo(fsl_lpspi);
+	wait_for_completion(&fsl_lpspi->xfer_done);
+
+	ret = fsl_lpspi_txfifo_empty(fsl_lpspi);
+	fsl_lpspi_read_rx_fifo(fsl_lpspi);
+
+	return ret;
+}
+
+static int fsl_lpspi_transfer_one_msg(struct spi_master *master,
+				      struct spi_message *msg)
+{
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+	struct spi_device *spi = msg->spi;
+	struct spi_transfer *xfer;
+	bool is_first_xfer = true;
+	u32 temp;
+	int ret;
+
+	msg->status = 0;
+	msg->actual_length = 0;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		fsl_lpspi_setup_transfer(spi, xfer);
+		fsl_lpspi_set_cmd(fsl_lpspi, is_first_xfer);
+
+		is_first_xfer = false;
+
+		ret = fsl_lpspi_transfer_one(master, spi, xfer);
+		if (ret < 0)
+			goto complete;
+
+		msg->actual_length += xfer->len;
+	}
+
+complete:
+	/* de-assert SS, then finalize current message */
+	temp = readl(fsl_lpspi->base + IMX7ULP_TCR);
+	temp &= ~TCR_CONTC;
+	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);
+
+	msg->status = ret;
+	spi_finalize_current_message(master);
+
+	return ret;
+}
+
+static irqreturn_t fsl_lpspi_isr(int irq, void *dev_id)
+{
+	struct fsl_lpspi_data *fsl_lpspi = dev_id;
+	u32 temp;
+
+	fsl_lpspi_intctrl(fsl_lpspi, 0);
+	temp = readl(fsl_lpspi->base + IMX7ULP_SR);
+
+	fsl_lpspi_read_rx_fifo(fsl_lpspi);
+
+	if (temp & SR_TDF) {
+		fsl_lpspi_write_tx_fifo(fsl_lpspi);
+
+		if (!fsl_lpspi->remain)
+			complete(&fsl_lpspi->xfer_done);
+
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static int fsl_lpspi_probe(struct platform_device *pdev)
+{
+	struct fsl_lpspi_data *fsl_lpspi;
+	struct spi_master *master;
+	struct resource *res;
+	int ret, irq;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct fsl_lpspi_data));
+	if (!master)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, master);
+
+	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
+	master->bus_num = pdev->id;
+
+	fsl_lpspi = spi_master_get_devdata(master);
+	fsl_lpspi->dev = &pdev->dev;
+
+	master->transfer_one_message = fsl_lpspi_transfer_one_msg;
+	master->prepare_message = fsl_lpspi_prepare_message;
+	master->unprepare_message = fsl_lpspi_unprepare_message;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
+	master->dev.of_node = pdev->dev.of_node;
+	master->bus_num = pdev->id;
+
+	init_completion(&fsl_lpspi->xfer_done);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	fsl_lpspi->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(fsl_lpspi->base)) {
+		ret = PTR_ERR(fsl_lpspi->base);
+		goto out_master_put;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		ret = irq;
+		goto out_master_put;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, fsl_lpspi_isr, 0,
+			       dev_name(&pdev->dev), fsl_lpspi);
+	if (ret) {
+		dev_err(&pdev->dev, "can't get irq%d: %d\n", irq, ret);
+		goto out_master_put;
+	}
+
+	fsl_lpspi->clk = devm_clk_get(&pdev->dev, "ipg");
+	if (IS_ERR(fsl_lpspi->clk)) {
+		ret = PTR_ERR(fsl_lpspi->clk);
+		goto out_master_put;
+	}
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "spi_register_master error.\n");
+		goto out_master_put;
+	}
+
+	return 0;
+
+out_master_put:
+	spi_master_put(master);
+
+	return ret;
+}
+
+static int fsl_lpspi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
+
+	clk_disable_unprepare(fsl_lpspi->clk);
+
+	return 0;
+}
+
+static struct platform_driver fsl_lpspi_driver = {
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .of_match_table = fsl_lpspi_dt_ids,
+		   },
+	.probe = fsl_lpspi_probe,
+	.remove = fsl_lpspi_remove,
+};
+module_platform_driver(fsl_lpspi_driver);
+
+MODULE_DESCRIPTION("LPSPI Master Controller driver");
+MODULE_AUTHOR("Gao Pan <pandy.gao-3arQi8VN3Tc@public.gmane.org>");
+MODULE_LICENSE("GPL v2");
-- 
2.10.2

--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

RE: [Patch V3 2/2] spi: imx: add lpspi bus driver

[Pandy Gao]

 From: Mark Brown <mailto:broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>  Sent: Wednesday, November 23, 2016 3:13 AM
> To: Pandy Gao <pandy.gao-3arQi8VN3Tc@public.gmane.org>
> Cc: robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org; linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Frank Li
> <frank.li-3arQi8VN3Tc@public.gmane.org>; Andy Duan <fugang.duan-3arQi8VN3Tc@public.gmane.org>
> Subject: Re: [Patch V3 2/2] spi: imx: add lpspi bus driver
> 
> On Tue, Nov 22, 2016 at 09:52:17PM +0800, Gao Pan wrote:
> > This patch adds lpspi driver to support new i.MX products which use
> > lpspi instead of ecspi.
> 
> I'll apply this but there's some small issues, can you please fix them up
> with incremental patches:
>
> > +static int fsl_lpspi_prepare_message(struct spi_master *master,
> > +				     struct spi_message *msg)
> > +{
> > +	struct fsl_lpspi_data *fsl_lpspi =
> spi_master_get_devdata(master);
> > +
> > +	return clk_prepare_enable(fsl_lpspi->clk);
> > +}
> 
> Rather than doing this per message it's a bit better to do it in
> prepare_transfer_hardware(), that way if there's a sequence of messages
> queued one after another we don't turn the clock on and off all the time.
> In practice it's likely to make a negligable difference to performance but
> it's just better practice.
> 
> > +static int fsl_lpspi_txfifo_empty(struct fsl_lpspi_data *fsl_lpspi) {
> > +	u32 txcnt;
> > +	unsigned long orig_jiffies = jiffies;
> > +
> > +	do {
> > +		txcnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;
> > +
> > +		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500)))
> {
> > +			dev_dbg(fsl_lpspi->dev, "txfifo empty
> timeout\n");
> > +			return -ETIMEDOUT;
> > +		}
> > +		schedule();
> 
> Call cond_resched() instead, it has the effect you're looking for in a more
> modern way.
 
Thanks, will submit  incremental patches to fix them up.

Best Regards
Gao Pan
--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html