Message-Id: <20230622113341.657842-4-fabrizio.castro.jz@renesas.com>
Date:   Thu, 22 Jun 2023 12:33:39 +0100
From:   Fabrizio Castro <fabrizio.castro.jz@...esas.com>
To:     Mark Brown <broonie@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
        Magnus Damm <magnus.damm@...il.com>,
        linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>
Subject: [PATCH v2 3/5] spi: Add support for Renesas CSI

The RZ/V2M SoC comes with the Clocked Serial Interface (CSI)
IP, which is a master/slave SPI controller.

This commit adds a driver to support CSI master mode.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
---

v2: edited includes in drivers/spi/spi-rzv2m-csi.c

 drivers/spi/Kconfig         |   6 +
 drivers/spi/Makefile        |   1 +
 drivers/spi/spi-rzv2m-csi.c | 667 ++++++++++++++++++++++++++++++++++++
 3 files changed, 674 insertions(+)
 create mode 100644 drivers/spi/spi-rzv2m-csi.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 14810d24733b..abbd1fb5fbc0 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -825,6 +825,12 @@ config SPI_RSPI
 	help
 	  SPI driver for Renesas RSPI and QSPI blocks.
 
+config SPI_RZV2M_CSI
+	tristate "Renesas RZV2M CSI controller"
+	depends on ARCH_RENESAS || COMPILE_TEST
+	help
+	  SPI driver for Renesas RZ/V2M Clocked Serial Interface (CSI)
+
 config SPI_QCOM_QSPI
 	tristate "QTI QSPI controller"
 	depends on ARCH_QCOM || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 28c4817a8a74..080c2c1b3ec1 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -113,6 +113,7 @@ obj-$(CONFIG_SPI_RB4XX)			+= spi-rb4xx.o
 obj-$(CONFIG_MACH_REALTEK_RTL)		+= spi-realtek-rtl.o
 obj-$(CONFIG_SPI_RPCIF)			+= spi-rpc-if.o
 obj-$(CONFIG_SPI_RSPI)			+= spi-rspi.o
+obj-$(CONFIG_SPI_RZV2M_CSI)		+= spi-rzv2m-csi.o
 obj-$(CONFIG_SPI_S3C64XX)		+= spi-s3c64xx.o
 obj-$(CONFIG_SPI_SC18IS602)		+= spi-sc18is602.o
 obj-$(CONFIG_SPI_SH)			+= spi-sh.o
diff --git a/drivers/spi/spi-rzv2m-csi.c b/drivers/spi/spi-rzv2m-csi.c
new file mode 100644
index 000000000000..14ad65da930d
--- /dev/null
+++ b/drivers/spi/spi-rzv2m-csi.c
@@ -0,0 +1,667 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Renesas RZ/V2M Clocked Serial Interface (CSI) driver
+ *
+ * Copyright (C) 2023 Renesas Electronics Corporation
+ */
+
+#include <linux/clk.h>
+#include <linux/count_zeros.h>
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+
+/* Registers */
+#define CSI_MODE		0x00	/* CSI mode control */
+#define CSI_CLKSEL		0x04	/* CSI clock select */
+#define CSI_CNT			0x08	/* CSI control */
+#define CSI_INT			0x0C	/* CSI interrupt status */
+#define CSI_IFIFOL		0x10	/* CSI receive FIFO level display */
+#define CSI_OFIFOL		0x14	/* CSI transmit FIFO level display */
+#define CSI_IFIFO		0x18	/* CSI receive window */
+#define CSI_OFIFO		0x1C	/* CSI transmit window */
+#define CSI_FIFOTRG		0x20	/* CSI FIFO trigger level */
+
+/* CSI_MODE */
+#define CSI_MODE_CSIE		BIT(7)
+#define CSI_MODE_TRMD		BIT(6)
+#define CSI_MODE_CCL		BIT(5)
+#define CSI_MODE_DIR		BIT(4)
+#define CSI_MODE_CSOT		BIT(0)
+
+#define CSI_MODE_SETUP		0x00000040
+
+/* CSI_CLKSEL */
+#define CSI_CLKSEL_CKP		BIT(17)
+#define CSI_CLKSEL_DAP		BIT(16)
+#define CSI_CLKSEL_SLAVE	BIT(15)
+#define CSI_CLKSEL_CKS		GENMASK(14, 1)
+
+/* CSI_CNT */
+#define CSI_CNT_CSIRST		BIT(28)
+#define CSI_CNT_R_TRGEN		BIT(19)
+#define CSI_CNT_UNDER_E		BIT(13)
+#define CSI_CNT_OVERF_E		BIT(12)
+#define CSI_CNT_TREND_E		BIT(9)
+#define CSI_CNT_CSIEND_E	BIT(8)
+#define CSI_CNT_T_TRGR_E	BIT(4)
+#define CSI_CNT_R_TRGR_E	BIT(0)
+
+/* CSI_INT */
+#define CSI_INT_UNDER		BIT(13)
+#define CSI_INT_OVERF		BIT(12)
+#define CSI_INT_TREND		BIT(9)
+#define CSI_INT_CSIEND		BIT(8)
+#define CSI_INT_T_TRGR		BIT(4)
+#define CSI_INT_R_TRGR		BIT(0)
+
+/* CSI_FIFOTRG */
+#define CSI_FIFOTRG_R_TRG       GENMASK(2, 0)
+
+#define CSI_FIFO_SIZE_BYTES	32
+#define CSI_FIFO_HALF_SIZE	16
+#define CSI_EN_DIS_TIMEOUT_US	100
+#define CSI_CKS_MAX		0x3FFF
+
+#define UNDERRUN_ERROR		BIT(0)
+#define OVERFLOW_ERROR		BIT(1)
+#define TX_TIMEOUT_ERROR	BIT(2)
+#define RX_TIMEOUT_ERROR	BIT(3)
+
+#define CSI_MAX_SPI_SCKO	8000000
+
+struct rzv2m_csi_priv {
+	void __iomem *base;
+	struct clk *csiclk;
+	struct clk *pclk;
+	struct device *dev;
+	struct spi_controller *controller;
+	const u8 *txbuf;
+	u8 *rxbuf;
+	int buffer_len;
+	int bytes_sent;
+	int bytes_received;
+	int bytes_to_transfer;
+	int words_to_transfer;
+	unsigned char bytes_per_word;
+	wait_queue_head_t wait;
+	u8 errors;
+	u32 status;
+};
+
+static const unsigned char x_trg[] = {
+	0, 1, 1, 2, 2, 2, 2, 3,
+	3, 3, 3, 3, 3, 3, 3, 4,
+	4, 4, 4, 4, 4, 4, 4, 4,
+	4, 4, 4, 4, 4, 4, 4, 5
+};
+
+static const unsigned char x_trg_words[] = {
+	1,  2,  2,  4,  4,  4,  4,  8,
+	8,  8,  8,  8,  8,  8,  8,  16,
+	16, 16, 16, 16, 16, 16, 16, 16,
+	16, 16, 16, 16, 16, 16, 16, 32
+};
+
+static void rzv2m_csi_reg_write_bit(const struct rzv2m_csi_priv *csi,
+				    int reg_offs, int bit_mask, u32 value)
+{
+	int nr_zeros;
+	u32 tmp;
+
+	nr_zeros = count_trailing_zeros(bit_mask);
+	value <<= nr_zeros;
+
+	tmp = (readl(csi->base + reg_offs) & ~bit_mask) | value;
+	writel(tmp, csi->base + reg_offs);
+}
+
+static int rzv2m_csi_sw_reset(struct rzv2m_csi_priv *csi, int assert)
+{
+	u32 reg;
+
+	rzv2m_csi_reg_write_bit(csi, CSI_CNT, CSI_CNT_CSIRST, assert);
+
+	if (assert) {
+		return readl_poll_timeout(csi->base + CSI_MODE, reg,
+					  !(reg & CSI_MODE_CSOT), 0,
+					  CSI_EN_DIS_TIMEOUT_US);
+	}
+
+	return 0;
+}
+
+static int rzv2m_csi_start_stop_operation(const struct rzv2m_csi_priv *csi,
+					  int enable, bool wait)
+{
+	u32 reg;
+
+	rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_CSIE, enable);
+
+	if (!enable && wait)
+		return readl_poll_timeout(csi->base + CSI_MODE, reg,
+					  !(reg & CSI_MODE_CSOT), 0,
+					  CSI_EN_DIS_TIMEOUT_US);
+
+	return 0;
+}
+
+static int rzv2m_csi_fill_txfifo(struct rzv2m_csi_priv *csi)
+{
+	int i;
+
+	if (readl(csi->base + CSI_OFIFOL))
+		return -EIO;
+
+	if (csi->bytes_per_word == 2) {
+		u16 *buf = (u16 *)csi->txbuf;
+
+		for (i = 0; i < csi->words_to_transfer; i++)
+			writel(buf[i], csi->base + CSI_OFIFO);
+	} else {
+		u8 *buf = (u8 *)csi->txbuf;
+
+		for (i = 0; i < csi->words_to_transfer; i++)
+			writel(buf[i], csi->base + CSI_OFIFO);
+	}
+
+	csi->txbuf += csi->bytes_to_transfer;
+	csi->bytes_sent += csi->bytes_to_transfer;
+
+	return 0;
+}
+
+static int rzv2m_csi_read_rxfifo(struct rzv2m_csi_priv *csi)
+{
+	int i;
+
+	if (readl(csi->base + CSI_IFIFOL) != csi->bytes_to_transfer)
+		return -EIO;
+
+	if (csi->bytes_per_word == 2) {
+		u16 *buf = (u16 *)csi->rxbuf;
+
+		for (i = 0; i < csi->words_to_transfer; i++)
+			buf[i] = (u16)readl(csi->base + CSI_IFIFO);
+	} else {
+		u8 *buf = (u8 *)csi->rxbuf;
+
+		for (i = 0; i < csi->words_to_transfer; i++)
+			buf[i] = (u8)readl(csi->base + CSI_IFIFO);
+	}
+
+	csi->rxbuf += csi->bytes_to_transfer;
+	csi->bytes_received += csi->bytes_to_transfer;
+
+	return 0;
+}
+
+static inline void rzv2m_csi_calc_current_transfer(struct rzv2m_csi_priv *csi)
+{
+	int bytes_transferred = max_t(int, csi->bytes_received, csi->bytes_sent);
+	int bytes_remaining = csi->buffer_len - bytes_transferred;
+	int to_transfer;
+
+	if (csi->txbuf)
+		/*
+		 * Leaving a little bit of headroom in the FIFOs makes it very
+		 * hard to raise an overflow error (which is only possible
+		 * when IP transmits and receives at the same time).
+		 */
+		to_transfer = min_t(int, CSI_FIFO_HALF_SIZE, bytes_remaining);
+	else
+		to_transfer = min_t(int, CSI_FIFO_SIZE_BYTES, bytes_remaining);
+
+	if (csi->bytes_per_word == 2)
+		to_transfer >>= 1;
+
+	/*
+	 * We can only choose a trigger level from a predefined set of values.
+	 * This will pick a value that is the greatest possible integer that's
+	 * less than or equal to the number of bytes we need to transfer.
+	 * This may result in multiple smaller transfers.
+	 */
+	csi->words_to_transfer = x_trg_words[to_transfer - 1];
+
+	if (csi->bytes_per_word == 2)
+		csi->bytes_to_transfer = csi->words_to_transfer << 1;
+	else
+		csi->bytes_to_transfer = csi->words_to_transfer;
+}
+
+static inline void rzv2m_csi_set_rx_fifo_trigger_level(struct rzv2m_csi_priv *csi)
+{
+	rzv2m_csi_reg_write_bit(csi, CSI_FIFOTRG, CSI_FIFOTRG_R_TRG,
+				x_trg[csi->words_to_transfer - 1]);
+}
+
+static inline void rzv2m_csi_enable_rx_trigger(struct rzv2m_csi_priv *csi,
+					       bool enable)
+{
+	rzv2m_csi_reg_write_bit(csi, CSI_CNT, CSI_CNT_R_TRGEN, enable);
+}
+
+static void rzv2m_csi_disable_irqs(const struct rzv2m_csi_priv *csi,
+				   u32 enable_bits)
+{
+	u32 cnt = readl(csi->base + CSI_CNT);
+
+	writel(cnt & ~enable_bits, csi->base + CSI_CNT);
+}
+
+static void rzv2m_csi_disable_all_irqs(struct rzv2m_csi_priv *csi)
+{
+	rzv2m_csi_disable_irqs(csi, CSI_CNT_R_TRGR_E | CSI_CNT_T_TRGR_E |
+			       CSI_CNT_CSIEND_E | CSI_CNT_TREND_E |
+			       CSI_CNT_OVERF_E | CSI_CNT_UNDER_E);
+}
+
+static inline void rzv2m_csi_clear_irqs(struct rzv2m_csi_priv *csi, u32 irqs)
+{
+	writel(irqs, csi->base + CSI_INT);
+}
+
+static void rzv2m_csi_clear_all_irqs(struct rzv2m_csi_priv *csi)
+{
+	rzv2m_csi_clear_irqs(csi, CSI_INT_UNDER | CSI_INT_OVERF |
+			     CSI_INT_TREND | CSI_INT_CSIEND |  CSI_INT_T_TRGR |
+			     CSI_INT_R_TRGR);
+}
+
+static void rzv2m_csi_enable_irqs(struct rzv2m_csi_priv *csi, u32 enable_bits)
+{
+	u32 cnt = readl(csi->base + CSI_CNT);
+
+	writel(cnt | enable_bits, csi->base + CSI_CNT);
+}
+
+static int rzv2m_csi_wait_for_interrupt(struct rzv2m_csi_priv *csi,
+					u32 wait_mask, u32 enable_bits)
+{
+	int ret;
+
+	rzv2m_csi_enable_irqs(csi, enable_bits);
+
+	ret = wait_event_timeout(csi->wait,
+				 ((csi->status & wait_mask) == wait_mask) ||
+				 csi->errors, HZ);
+
+	rzv2m_csi_disable_irqs(csi, enable_bits);
+
+	if (csi->errors)
+		return -EIO;
+
+	if (!ret)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int rzv2m_csi_wait_for_tx_empty(struct rzv2m_csi_priv *csi)
+{
+	int ret;
+
+	if (readl(csi->base + CSI_OFIFOL) == 0)
+		return 0;
+
+	ret = rzv2m_csi_wait_for_interrupt(csi, CSI_INT_TREND, CSI_CNT_TREND_E);
+
+	if (ret == -ETIMEDOUT)
+		csi->errors |= TX_TIMEOUT_ERROR;
+
+	return ret;
+}
+
+static inline int rzv2m_csi_wait_for_rx_ready(struct rzv2m_csi_priv *csi)
+{
+	int ret;
+
+	if (readl(csi->base + CSI_IFIFOL) == csi->bytes_to_transfer)
+		return 0;
+
+	ret = rzv2m_csi_wait_for_interrupt(csi, CSI_INT_R_TRGR,
+					   CSI_CNT_R_TRGR_E);
+
+	if (ret == -ETIMEDOUT)
+		csi->errors |= RX_TIMEOUT_ERROR;
+
+	return ret;
+}
+
+static irqreturn_t rzv2m_csi_irq_handler(int irq, void *data)
+{
+	struct rzv2m_csi_priv *csi = (struct rzv2m_csi_priv *)data;
+
+	csi->status = readl(csi->base + CSI_INT);
+	rzv2m_csi_disable_irqs(csi, csi->status);
+
+	if (csi->status & CSI_INT_OVERF)
+		csi->errors |= OVERFLOW_ERROR;
+	if (csi->status & CSI_INT_UNDER)
+		csi->errors |= UNDERRUN_ERROR;
+
+	wake_up(&csi->wait);
+
+	return IRQ_HANDLED;
+}
+
+static void rzv2m_csi_setup_clock(struct rzv2m_csi_priv *csi, u32 spi_hz)
+{
+	unsigned long csiclk_rate = clk_get_rate(csi->csiclk);
+	unsigned long pclk_rate = clk_get_rate(csi->pclk);
+	unsigned long csiclk_rate_limit = pclk_rate >> 1;
+	u32 cks;
+
+	/*
+	 * There is a restriction on the frequency of CSICLK, it has to be <=
+	 * PCLK / 2.
+	 */
+	if (csiclk_rate > csiclk_rate_limit) {
+		clk_set_rate(csi->csiclk, csiclk_rate >> 1);
+		csiclk_rate = clk_get_rate(csi->csiclk);
+	} else if ((csiclk_rate << 1) <= csiclk_rate_limit) {
+		clk_set_rate(csi->csiclk, csiclk_rate << 1);
+		csiclk_rate = clk_get_rate(csi->csiclk);
+	}
+
+	spi_hz = spi_hz > CSI_MAX_SPI_SCKO ? CSI_MAX_SPI_SCKO : spi_hz;
+
+	cks = DIV_ROUND_UP(csiclk_rate, spi_hz << 1);
+	if (cks > CSI_CKS_MAX)
+		cks = CSI_CKS_MAX;
+
+	dev_dbg(csi->dev, "SPI clk rate is %ldHz\n", csiclk_rate / (cks << 1));
+
+	rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_CKS, cks);
+}
+
+static void rzv2m_csi_setup_operating_mode(struct rzv2m_csi_priv *csi,
+					   struct spi_transfer *t)
+{
+	if (t->rx_buf && !t->tx_buf)
+		/* Reception-only mode */
+		rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_TRMD, 0);
+	else
+		/* Send and receive mode */
+		rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_TRMD, 1);
+
+	csi->bytes_per_word = t->bits_per_word / 8;
+	rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_CCL,
+				csi->bytes_per_word == 2);
+}
+
+static int rzv2m_csi_setup(struct spi_device *spi)
+{
+	struct rzv2m_csi_priv *csi = spi_controller_get_devdata(spi->controller);
+	int ret;
+
+	rzv2m_csi_sw_reset(csi, 0);
+
+	writel(CSI_MODE_SETUP, csi->base + CSI_MODE);
+
+	/* Setup clock polarity and phase timing */
+	rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_CKP,
+				!(spi->mode & SPI_CPOL));
+	rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_DAP,
+				!(spi->mode & SPI_CPHA));
+
+	/* Setup serial data order */
+	rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_DIR,
+				!!(spi->mode & SPI_LSB_FIRST));
+
+	/* Set the operation mode as master */
+	rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_SLAVE, 0);
+
+	/* Give the IP a SW reset */
+	ret = rzv2m_csi_sw_reset(csi, 1);
+	if (ret)
+		return ret;
+	rzv2m_csi_sw_reset(csi, 0);
+
+	/*
+	 * We need to enable the communication so that the clock will settle
+	 * for the right polarity before enabling the CS.
+	 */
+	rzv2m_csi_start_stop_operation(csi, 1, false);
+	udelay(10);
+	rzv2m_csi_start_stop_operation(csi, 0, false);
+
+	return 0;
+}
+
+static int rzv2m_csi_pio_transfer(struct rzv2m_csi_priv *csi)
+{
+	bool tx_completed = csi->txbuf ? false : true;
+	bool rx_completed = csi->rxbuf ? false : true;
+	int ret = 0;
+
+	/* Make sure the TX FIFO is empty */
+	writel(0, csi->base + CSI_OFIFOL);
+
+	csi->bytes_sent = 0;
+	csi->bytes_received = 0;
+	csi->errors = 0;
+
+	rzv2m_csi_disable_all_irqs(csi);
+	rzv2m_csi_clear_all_irqs(csi);
+	rzv2m_csi_enable_rx_trigger(csi, true);
+
+	while (!tx_completed || !rx_completed) {
+		/*
+		 * Decide how many words we are going to transfer during
+		 * this cycle (for both TX and RX), then set the RX FIFO trigger
+		 * level accordingly. No need to set a trigger level for the
+		 * TX FIFO, as this IP comes with an interrupt that fires when
+		 * the TX FIFO is empty.
+		 */
+		rzv2m_csi_calc_current_transfer(csi);
+		rzv2m_csi_set_rx_fifo_trigger_level(csi);
+
+		rzv2m_csi_enable_irqs(csi, CSI_INT_OVERF | CSI_INT_UNDER);
+
+		/* Make sure the RX FIFO is empty */
+		writel(0, csi->base + CSI_IFIFOL);
+
+		writel(readl(csi->base + CSI_INT), csi->base + CSI_INT);
+		csi->status = 0;
+
+		rzv2m_csi_start_stop_operation(csi, 1, false);
+
+		/* TX */
+		if (csi->txbuf) {
+			ret = rzv2m_csi_fill_txfifo(csi);
+			if (ret)
+				break;
+
+			ret = rzv2m_csi_wait_for_tx_empty(csi);
+			if (ret)
+				break;
+
+			if (csi->bytes_sent == csi->buffer_len)
+				tx_completed = true;
+		}
+
+		/*
+		 * Make sure the RX FIFO contains the desired number of words.
+		 * We then either flush its content, or we copy it onto
+		 * csi->rxbuf.
+		 */
+		ret = rzv2m_csi_wait_for_rx_ready(csi);
+		if (ret)
+			break;
+
+		/* RX */
+		if (csi->rxbuf) {
+			rzv2m_csi_start_stop_operation(csi, 0, false);
+
+			ret = rzv2m_csi_read_rxfifo(csi);
+			if (ret)
+				break;
+
+			if (csi->bytes_received == csi->buffer_len)
+				rx_completed = true;
+		}
+
+		ret = rzv2m_csi_start_stop_operation(csi, 0, true);
+		if (ret)
+			goto pio_quit;
+
+		if (csi->errors) {
+			ret = -EIO;
+			goto pio_quit;
+		}
+	}
+
+	rzv2m_csi_start_stop_operation(csi, 0, true);
+
+pio_quit:
+	rzv2m_csi_disable_all_irqs(csi);
+	rzv2m_csi_enable_rx_trigger(csi, false);
+	rzv2m_csi_clear_all_irqs(csi);
+
+	return ret;
+}
+
+static int rzv2m_csi_transfer_one(struct spi_controller *controller,
+				  struct spi_device *spi,
+				  struct spi_transfer *transfer)
+{
+	struct rzv2m_csi_priv *csi = spi_controller_get_devdata(controller);
+	struct device *dev = csi->dev;
+	int ret;
+
+	csi->txbuf = transfer->tx_buf;
+	csi->rxbuf = transfer->rx_buf;
+	csi->buffer_len = transfer->len;
+
+	rzv2m_csi_setup_operating_mode(csi, transfer);
+
+	rzv2m_csi_setup_clock(csi, transfer->speed_hz);
+
+	ret = rzv2m_csi_pio_transfer(csi);
+	if (ret) {
+		if (csi->errors & UNDERRUN_ERROR)
+			dev_err(dev, "Underrun error\n");
+		if (csi->errors & OVERFLOW_ERROR)
+			dev_err(dev, "Overflow error\n");
+		if (csi->errors & TX_TIMEOUT_ERROR)
+			dev_err(dev, "TX timeout error\n");
+		if (csi->errors & RX_TIMEOUT_ERROR)
+			dev_err(dev, "RX timeout error\n");
+	}
+
+	return ret;
+}
+
+static int rzv2m_csi_probe(struct platform_device *pdev)
+{
+	struct spi_controller *controller;
+	struct device *dev = &pdev->dev;
+	struct rzv2m_csi_priv *csi;
+	struct reset_control *rstc;
+	int irq;
+	int ret;
+
+	controller = devm_spi_alloc_master(dev, sizeof(*csi));
+	if (!controller)
+		return -ENOMEM;
+
+	csi = spi_controller_get_devdata(controller);
+	platform_set_drvdata(pdev, csi);
+
+	csi->dev = dev;
+	csi->controller = controller;
+
+	csi->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(csi->base))
+		return PTR_ERR(csi->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	csi->csiclk = devm_clk_get(dev, "csiclk");
+	if (IS_ERR(csi->csiclk))
+		return dev_err_probe(dev, PTR_ERR(csi->csiclk),
+				     "could not get csiclk\n");
+
+	csi->pclk = devm_clk_get(dev, "pclk");
+	if (IS_ERR(csi->pclk))
+		return dev_err_probe(dev, PTR_ERR(csi->pclk),
+				     "could not get pclk\n");
+
+	rstc = devm_reset_control_get_shared(dev, NULL);
+	if (IS_ERR(rstc))
+		return dev_err_probe(dev, PTR_ERR(rstc), "Missing reset ctrl\n");
+
+	init_waitqueue_head(&csi->wait);
+
+	controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST;
+	controller->dev.of_node = pdev->dev.of_node;
+	controller->bits_per_word_mask = SPI_BPW_MASK(16) | SPI_BPW_MASK(8);
+	controller->setup = rzv2m_csi_setup;
+	controller->transfer_one = rzv2m_csi_transfer_one;
+	controller->use_gpio_descriptors = true;
+
+	ret = devm_request_irq(dev, irq, rzv2m_csi_irq_handler, 0,
+			       dev_name(dev), csi);
+	if (ret)
+		return dev_err_probe(dev, ret, "cannot request IRQ\n");
+
+	/*
+	 * The reset also affects other HW that is not under the control
+	 * of Linux. Therefore, all we can do is make sure the reset is
+	 * deasserted.
+	 */
+	reset_control_deassert(rstc);
+
+	/* Make sure the IP is in SW reset state */
+	ret = rzv2m_csi_sw_reset(csi, 1);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(csi->csiclk);
+	if (ret)
+		return dev_err_probe(dev, ret, "could not enable csiclk\n");
+
+	ret = spi_register_controller(controller);
+	if (ret) {
+		clk_disable_unprepare(csi->csiclk);
+		return dev_err_probe(dev, ret, "register controller failed\n");
+	}
+
+	return 0;
+}
+
+static int rzv2m_csi_remove(struct platform_device *pdev)
+{
+	struct rzv2m_csi_priv *csi = platform_get_drvdata(pdev);
+
+	spi_unregister_controller(csi->controller);
+	rzv2m_csi_sw_reset(csi, 1);
+	clk_disable_unprepare(csi->csiclk);
+
+	return 0;
+}
+
+static const struct of_device_id rzv2m_csi_match[] = {
+	{ .compatible = "renesas,rzv2m-csi" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rzv2m_csi_match);
+
+static struct platform_driver rzv2m_csi_drv = {
+	.probe = rzv2m_csi_probe,
+	.remove = rzv2m_csi_remove,
+	.driver = {
+		.name = "rzv2m_csi",
+		.of_match_table = rzv2m_csi_match,
+	},
+};
+module_platform_driver(rzv2m_csi_drv);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Fabrizio Castro <castro.fabrizio.jz@...esas.com>");
+MODULE_DESCRIPTION("Clocked Serial Interface Driver");
-- 
2.34.1

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