[PATCH V5 3/3] spi: spi-geni-qcom: Add SPI driver support for GENI based QUP

[Alok Chauhan]

From: Girish Mahadevan <girishm@xxxxxxxxxxxxxx>

This driver supports GENI based SPI Controller in the Qualcomm SOCs. The
Qualcomm Generic Interface (GENI) is a programmable module supporting a
wide range of serial interfaces including SPI. This driver supports SPI
operations using FIFO mode of transfer.

Signed-off-by: Girish Mahadevan <girishm@xxxxxxxxxxxxxx>
Signed-off-by: Dilip Kota <dkota@xxxxxxxxxxxxxx>
Signed-off-by: Alok Chauhan <alokc@xxxxxxxxxxxxxx>
---
 drivers/spi/Kconfig         |  12 +
 drivers/spi/Makefile        |   1 +
 drivers/spi/spi-geni-qcom.c | 703 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 716 insertions(+)
 create mode 100644 drivers/spi/spi-geni-qcom.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 671d078..51edc76 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -533,6 +533,18 @@ config SPI_QUP
 	  This driver can also be built as a module.  If so, the module
 	  will be called spi_qup.
 
+config SPI_QCOM_GENI
+	tristate "Qualcomm GENI based SPI controller"
+	depends on QCOM_GENI_SE
+	help
+	  This driver supports GENI serial engine based SPI controller in
+	  master mode on the Qualcomm Technologies Inc.'s SoCs. If you say
+	  yes to this option, support will be included for the built-in SPI
+	  interface on the Qualcomm Technologies Inc.'s SoCs.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called spi-geni-qcom.
+
 config SPI_S3C24XX
 	tristate "Samsung S3C24XX series SPI"
 	depends on ARCH_S3C24XX
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index a90d559..b057c9c 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -74,6 +74,7 @@ obj-$(CONFIG_SPI_PPC4xx)		+= spi-ppc4xx.o
 spi-pxa2xx-platform-objs		:= spi-pxa2xx.o spi-pxa2xx-dma.o
 obj-$(CONFIG_SPI_PXA2XX)		+= spi-pxa2xx-platform.o
 obj-$(CONFIG_SPI_PXA2XX_PCI)		+= spi-pxa2xx-pci.o
+obj-$(CONFIG_SPI_QCOM_GENI)		+= spi-geni-qcom.o
 obj-$(CONFIG_SPI_QUP)			+= spi-qup.o
 obj-$(CONFIG_SPI_ROCKCHIP)		+= spi-rockchip.o
 obj-$(CONFIG_SPI_RB4XX)			+= spi-rb4xx.o
diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
new file mode 100644
index 0000000..6432ecc
--- /dev/null
+++ b/drivers/spi/spi-geni-qcom.c
@@ -0,0 +1,703 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2017-2018, The Linux foundation. All rights reserved.
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/qcom-geni-se.h>
+#include <linux/spi/spi.h>
+#include <linux/spinlock.h>
+
+/* SPI SE specific registers and respective register fields */
+#define SE_SPI_CPHA		0x224
+#define CPHA			BIT(0)
+
+#define SE_SPI_LOOPBACK		0x22c
+#define LOOPBACK_ENABLE		0x1
+#define NORMAL_MODE		0x0
+#define LOOPBACK_MSK		GENMASK(1, 0)
+
+#define SE_SPI_CPOL		0x230
+#define CPOL			BIT(2)
+
+#define SE_SPI_DEMUX_OUTPUT_INV	0x24c
+#define CS_DEMUX_OUTPUT_INV_MSK	GENMASK(3, 0)
+
+#define SE_SPI_DEMUX_SEL	0x250
+#define CS_DEMUX_OUTPUT_SEL	GENMASK(3, 0)
+
+#define SE_SPI_TRANS_CFG	0x25c
+#define CS_TOGGLE		BIT(0)
+
+#define SE_SPI_WORD_LEN		0x268
+#define WORD_LEN_MSK		GENMASK(9, 0)
+#define MIN_WORD_LEN		4
+
+#define SE_SPI_TX_TRANS_LEN	0x26c
+#define SE_SPI_RX_TRANS_LEN	0x270
+#define TRANS_LEN_MSK		GENMASK(23, 0)
+
+#define SE_SPI_PRE_POST_CMD_DLY	0x274
+
+#define SE_SPI_DELAY_COUNTERS	0x278
+#define SPI_INTER_WORDS_DELAY_MSK	GENMASK(9, 0)
+#define SPI_CS_CLK_DELAY_MSK		GENMASK(19, 10)
+#define SPI_CS_CLK_DELAY_SHFT		10
+
+/* M_CMD OP codes for SPI */
+#define SPI_TX_ONLY		1
+#define SPI_RX_ONLY		2
+#define SPI_FULL_DUPLEX		3
+#define SPI_TX_RX		7
+#define SPI_CS_ASSERT		8
+#define SPI_CS_DEASSERT		9
+#define SPI_SCK_ONLY		10
+/* M_CMD params for SPI */
+#define SPI_PRE_CMD_DELAY	BIT(0)
+#define TIMESTAMP_BEFORE	BIT(1)
+#define FRAGMENTATION		BIT(2)
+#define TIMESTAMP_AFTER		BIT(3)
+#define POST_CMD_DELAY		BIT(4)
+
+/* SPI M_COMMAND OPCODE */
+enum spi_mcmd_code {
+	CMD_NONE,
+	CMD_XFER,
+	CMD_CS,
+	CMD_CANCEL,
+};
+
+
+struct spi_geni_master {
+	struct geni_se se;
+	struct device *dev;
+	u32 tx_fifo_depth;
+	u32 fifo_width_bits;
+	u32 tx_wm;
+	unsigned long cur_speed_hz;
+	unsigned int cur_bits_per_word;
+	unsigned int tx_rem_bytes;
+	unsigned int rx_rem_bytes;
+	const struct spi_transfer *cur_xfer;
+	struct completion xfer_done;
+	unsigned int oversampling;
+	spinlock_t lock;
+	unsigned int cur_mcmd;
+	int irq;
+};
+
+static void handle_fifo_timeout(struct spi_master *spi,
+				struct spi_message *msg);
+
+static int get_spi_clk_cfg(unsigned int speed_hz,
+			struct spi_geni_master *mas,
+			unsigned int *clk_idx,
+			unsigned int *clk_div)
+{
+	unsigned long sclk_freq;
+	unsigned int actual_hz;
+	struct geni_se *se = &mas->se;
+	int ret;
+
+	ret = geni_se_clk_freq_match(&mas->se,
+				speed_hz * mas->oversampling,
+				clk_idx, &sclk_freq, false);
+	if (ret) {
+		dev_err(mas->dev, "Failed(%d) to find src clk for %dHz\n",
+							ret, speed_hz);
+		return ret;
+	}
+
+	*clk_div = DIV_ROUND_UP(sclk_freq, mas->oversampling * speed_hz);
+	actual_hz = sclk_freq / (mas->oversampling * *clk_div);
+
+	dev_dbg(mas->dev, "req %u=>%u sclk %lu, idx %d, div %d\n", speed_hz,
+				actual_hz, sclk_freq, *clk_idx, *clk_div);
+	ret = clk_set_rate(se->clk, sclk_freq);
+	if (ret)
+		dev_err(mas->dev, "clk_set_rate failed %d\n", ret);
+	return ret;
+}
+
+static void spi_geni_set_cs(struct spi_device *slv, bool set_flag)
+{
+	struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
+	struct spi_master *spi = dev_get_drvdata(mas->dev);
+	struct geni_se *se = &mas->se;
+	unsigned long timeout;
+
+	reinit_completion(&mas->xfer_done);
+	pm_runtime_get_sync(mas->dev);
+	if (!(slv->mode & SPI_CS_HIGH))
+		set_flag = !set_flag;
+
+	mas->cur_mcmd = CMD_CS;
+	if (set_flag)
+		geni_se_setup_m_cmd(se, SPI_CS_ASSERT, 0);
+	else
+		geni_se_setup_m_cmd(se, SPI_CS_DEASSERT, 0);
+
+	timeout = wait_for_completion_timeout(&mas->xfer_done, HZ);
+	if (!timeout)
+		handle_fifo_timeout(spi, NULL);
+
+	pm_runtime_put(mas->dev);
+}
+
+static void spi_setup_word_len(struct spi_geni_master *mas, u16 mode,
+					unsigned int bits_per_word)
+{
+	unsigned int pack_words;
+	bool msb_first = (mode & SPI_LSB_FIRST) ? false : true;
+	struct geni_se *se = &mas->se;
+	u32 word_len;
+
+	word_len = readl(se->base + SE_SPI_WORD_LEN);
+
+	/*
+	 * If bits_per_word isn't a byte aligned value, set the packing to be
+	 * 1 SPI word per FIFO word.
+	 */
+	if (!(mas->fifo_width_bits % bits_per_word))
+		pack_words = mas->fifo_width_bits / bits_per_word;
+	else
+		pack_words = 1;
+	word_len &= ~WORD_LEN_MSK;
+	word_len |= ((bits_per_word - MIN_WORD_LEN) & WORD_LEN_MSK);
+	geni_se_config_packing(&mas->se, bits_per_word, pack_words, msb_first,
+								true, true);
+	writel(word_len, se->base + SE_SPI_WORD_LEN);
+}
+
+static int setup_fifo_params(struct spi_device *spi_slv,
+					struct spi_master *spi)
+{
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+	struct geni_se *se = &mas->se;
+	u32 loopback_cfg, cpol, cpha, demux_output_inv;
+	u32 demux_sel, clk_sel, m_clk_cfg, idx, div;
+	int ret;
+
+	loopback_cfg = readl(se->base + SE_SPI_LOOPBACK);
+	cpol = readl(se->base + SE_SPI_CPOL);
+	cpha = readl(se->base + SE_SPI_CPHA);
+	demux_output_inv = 0;
+	loopback_cfg &= ~LOOPBACK_MSK;
+	cpol &= ~CPOL;
+	cpha &= ~CPHA;
+
+	if (spi_slv->mode & SPI_LOOP)
+		loopback_cfg |= LOOPBACK_ENABLE;
+
+	if (spi_slv->mode & SPI_CPOL)
+		cpol |= CPOL;
+
+	if (spi_slv->mode & SPI_CPHA)
+		cpha |= CPHA;
+
+	if (spi_slv->mode & SPI_CS_HIGH)
+		demux_output_inv = BIT(spi_slv->chip_select);
+
+	demux_sel = spi_slv->chip_select;
+	mas->cur_speed_hz = spi_slv->max_speed_hz;
+	mas->cur_bits_per_word = spi_slv->bits_per_word;
+
+	ret = get_spi_clk_cfg(mas->cur_speed_hz, mas, &idx, &div);
+	if (ret) {
+		dev_err(mas->dev, "Err setting clks ret(%d) for %ld\n",
+							ret, mas->cur_speed_hz);
+		return ret;
+	}
+
+	clk_sel = idx & CLK_SEL_MSK;
+	m_clk_cfg = (div << CLK_DIV_SHFT) | SER_CLK_EN;
+	spi_setup_word_len(mas, spi_slv->mode, spi_slv->bits_per_word);
+	writel(loopback_cfg, se->base + SE_SPI_LOOPBACK);
+	writel(demux_sel, se->base + SE_SPI_DEMUX_SEL);
+	writel(cpha, se->base + SE_SPI_CPHA);
+	writel(cpol, se->base + SE_SPI_CPOL);
+	writel(demux_output_inv, se->base + SE_SPI_DEMUX_OUTPUT_INV);
+	writel(clk_sel, se->base + SE_GENI_CLK_SEL);
+	writel(m_clk_cfg, se->base + GENI_SER_M_CLK_CFG);
+	return 0;
+}
+
+static int spi_geni_prepare_message(struct spi_master *spi,
+					struct spi_message *spi_msg)
+{
+	int ret;
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+	struct geni_se *se = &mas->se;
+
+	geni_se_select_mode(se, GENI_SE_FIFO);
+	reinit_completion(&mas->xfer_done);
+	ret = setup_fifo_params(spi_msg->spi, spi);
+	if (ret)
+		dev_err(mas->dev, "Couldn't select mode %d\n", ret);
+	return ret;
+}
+
+static int spi_geni_init(struct spi_geni_master *mas)
+{
+	struct geni_se *se = &mas->se;
+	unsigned int proto, major, minor, ver;
+
+	pm_runtime_get_sync(mas->dev);
+
+	proto = geni_se_read_proto(se);
+	if (proto != GENI_SE_SPI) {
+		dev_err(mas->dev, "Invalid proto %d\n", proto);
+		pm_runtime_put(mas->dev);
+		return -ENXIO;
+	}
+	mas->tx_fifo_depth = geni_se_get_tx_fifo_depth(se);
+
+	/* Width of Tx and Rx FIFO is same */
+	mas->fifo_width_bits = geni_se_get_tx_fifo_width(se);
+
+	/*
+	 * Hardware programming guide suggests to configure
+	 * RX FIFO RFR level to fifo_depth-2.
+	 */
+	geni_se_init(se, 0x0, mas->tx_fifo_depth - 2);
+	/* Transmit an entire FIFO worth of data per IRQ */
+	mas->tx_wm = 1;
+	ver = geni_se_get_qup_hw_version(se);
+	major = GENI_SE_VERSION_MAJOR(ver);
+	minor = GENI_SE_VERSION_MINOR(ver);
+
+	if (major == 1 && minor == 0)
+		mas->oversampling = 2;
+	else
+		mas->oversampling = 1;
+
+	pm_runtime_put(mas->dev);
+	return 0;
+}
+
+static void setup_fifo_xfer(struct spi_transfer *xfer,
+				struct spi_geni_master *mas,
+				u16 mode, struct spi_master *spi)
+{
+	u32 m_cmd = 0;
+	u32 spi_tx_cfg, len;
+	struct geni_se *se = &mas->se;
+
+	spi_tx_cfg = readl(se->base + SE_SPI_TRANS_CFG);
+	if (xfer->bits_per_word != mas->cur_bits_per_word) {
+		spi_setup_word_len(mas, mode, xfer->bits_per_word);
+		mas->cur_bits_per_word = xfer->bits_per_word;
+	}
+
+	/* Speed and bits per word can be overridden per transfer */
+	if (xfer->speed_hz != mas->cur_speed_hz) {
+		int ret;
+		u32 clk_sel, m_clk_cfg;
+		unsigned int idx, div;
+
+		ret = get_spi_clk_cfg(xfer->speed_hz, mas, &idx, &div);
+		if (ret) {
+			dev_err(mas->dev, "Err setting clks:%d\n", ret);
+			return;
+		}
+		/*
+		 * SPI core clock gets configured with the requested frequency
+		 * or the frequency closer to the requested frequency.
+		 * For that reason requested frequency is stored in the
+		 * cur_speed_hz and referred in the consecutive transfer instead
+		 * of calling clk_get_rate() API.
+		 */
+		mas->cur_speed_hz = xfer->speed_hz;
+		clk_sel = idx & CLK_SEL_MSK;
+		m_clk_cfg = (div << CLK_DIV_SHFT) | SER_CLK_EN;
+		writel(clk_sel, se->base + SE_GENI_CLK_SEL);
+		writel(m_clk_cfg, se->base + GENI_SER_M_CLK_CFG);
+	}
+
+	mas->tx_rem_bytes = 0;
+	mas->rx_rem_bytes = 0;
+	if (xfer->tx_buf && xfer->rx_buf)
+		m_cmd = SPI_FULL_DUPLEX;
+	else if (xfer->tx_buf)
+		m_cmd = SPI_TX_ONLY;
+	else if (xfer->rx_buf)
+		m_cmd = SPI_RX_ONLY;
+
+	spi_tx_cfg &= ~CS_TOGGLE;
+
+	if (!(mas->cur_bits_per_word % MIN_WORD_LEN))
+		len = xfer->len * BITS_PER_BYTE / mas->cur_bits_per_word;
+	else
+		len = xfer->len / (mas->cur_bits_per_word / BITS_PER_BYTE + 1);
+	len &= TRANS_LEN_MSK;
+
+	mas->cur_xfer = xfer;
+	if (m_cmd & SPI_TX_ONLY) {
+		mas->tx_rem_bytes = xfer->len;
+		writel(len, se->base + SE_SPI_TX_TRANS_LEN);
+	}
+
+	if (m_cmd & SPI_RX_ONLY) {
+		writel(len, se->base + SE_SPI_RX_TRANS_LEN);
+		mas->rx_rem_bytes = xfer->len;
+	}
+	writel(spi_tx_cfg, se->base + SE_SPI_TRANS_CFG);
+	mas->cur_mcmd = CMD_XFER;
+	geni_se_setup_m_cmd(se, m_cmd, FRAGMENTATION);
+
+	/*
+	 * TX_WATERMARK_REG should be set after SPI configuration and
+	 * setting up GENI SE engine, as driver starts data transfer
+	 * for the watermark interrupt.
+	 */
+	if (m_cmd & SPI_TX_ONLY)
+		writel(mas->tx_wm, se->base + SE_GENI_TX_WATERMARK_REG);
+}
+
+static void handle_fifo_timeout(struct spi_master *spi,
+				struct spi_message *msg)
+{
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+	unsigned long time_left, flags;
+	struct geni_se *se = &mas->se;
+
+	spin_lock_irqsave(&mas->lock, flags);
+	reinit_completion(&mas->xfer_done);
+	mas->cur_mcmd = CMD_CANCEL;
+	geni_se_cancel_m_cmd(se);
+	writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
+	spin_unlock_irqrestore(&mas->lock, flags);
+	time_left = wait_for_completion_timeout(&mas->xfer_done, HZ);
+	if (time_left)
+		return;
+
+	spin_lock_irqsave(&mas->lock, flags);
+	reinit_completion(&mas->xfer_done);
+	geni_se_abort_m_cmd(se);
+	spin_unlock_irqrestore(&mas->lock, flags);
+	time_left = wait_for_completion_timeout(&mas->xfer_done, HZ);
+	if (!time_left)
+		dev_err(mas->dev, "Failed to cancel/abort m_cmd\n");
+}
+
+static int spi_geni_transfer_one(struct spi_master *spi,
+				struct spi_device *slv,
+				struct spi_transfer *xfer)
+{
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+
+	/* Terminate and return success for 0 byte length transfer */
+	if (!xfer->len)
+		return 0;
+
+	setup_fifo_xfer(xfer, mas, slv->mode, spi);
+	return 1;
+}
+
+static unsigned int geni_byte_per_fifo_word(struct spi_geni_master *mas)
+{
+	/*
+	 * Calculate how many bytes we'll put in each FIFO word.  If the
+	 * transfer words don't pack cleanly into a FIFO word we'll just put
+	 * one transfer word in each FIFO word.  If they do pack we'll pack 'em.
+	 */
+	if (mas->fifo_width_bits % mas->cur_bits_per_word)
+		return roundup_pow_of_two(DIV_ROUND_UP(mas->cur_bits_per_word,
+						       BITS_PER_BYTE));
+
+	return mas->fifo_width_bits / BITS_PER_BYTE;
+}
+
+static void geni_spi_handle_tx(struct spi_geni_master *mas)
+{
+	struct geni_se *se = &mas->se;
+	unsigned int max_bytes;
+	const u8 *tx_buf;
+	unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
+	unsigned int i = 0;
+
+	max_bytes = (mas->tx_fifo_depth - mas->tx_wm) * bytes_per_fifo_word;
+	if (mas->tx_rem_bytes < max_bytes)
+		max_bytes = mas->tx_rem_bytes;
+
+	tx_buf = mas->cur_xfer->tx_buf + mas->cur_xfer->len - mas->tx_rem_bytes;
+	while (i < max_bytes) {
+		unsigned int j;
+		unsigned int bytes_to_write;
+		u32 fifo_word = 0;
+		u8 *fifo_byte = (u8 *)&fifo_word;
+
+		bytes_to_write = min(bytes_per_fifo_word, max_bytes - i);
+		for (j = 0; j < bytes_to_write; j++)
+			fifo_byte[j] = tx_buf[i++];
+		iowrite32_rep(se->base + SE_GENI_TX_FIFOn, &fifo_word, 1);
+	}
+	mas->tx_rem_bytes -= max_bytes;
+	if (!mas->tx_rem_bytes)
+		writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
+}
+
+static void geni_spi_handle_rx(struct spi_geni_master *mas)
+{
+	struct geni_se *se = &mas->se;
+	u32 rx_fifo_status;
+	unsigned int rx_bytes;
+	unsigned int rx_last_byte_valid;
+	u8 *rx_buf;
+	unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
+	unsigned int i = 0;
+
+	rx_fifo_status = readl(se->base + SE_GENI_RX_FIFO_STATUS);
+	rx_bytes = (rx_fifo_status & RX_FIFO_WC_MSK) * bytes_per_fifo_word;
+	if (rx_fifo_status & RX_LAST) {
+		rx_last_byte_valid = rx_fifo_status & RX_LAST_BYTE_VALID_MSK;
+		rx_last_byte_valid >>= RX_LAST_BYTE_VALID_SHFT;
+		if (rx_last_byte_valid && rx_last_byte_valid < 4)
+			rx_bytes -= bytes_per_fifo_word - rx_last_byte_valid;
+	}
+	if (mas->rx_rem_bytes < rx_bytes)
+		rx_bytes = mas->rx_rem_bytes;
+
+	rx_buf = mas->cur_xfer->rx_buf + mas->cur_xfer->len - mas->rx_rem_bytes;
+	while (i < rx_bytes) {
+		u32 fifo_word = 0;
+		u8 *fifo_byte = (u8 *)&fifo_word;
+		unsigned int bytes_to_read;
+		unsigned int j;
+
+		bytes_to_read = min(bytes_per_fifo_word, rx_bytes - i);
+		ioread32_rep(se->base + SE_GENI_RX_FIFOn, &fifo_word, 1);
+		for (j = 0; j < bytes_to_read; j++)
+			rx_buf[i++] = fifo_byte[j];
+	}
+	mas->rx_rem_bytes -= rx_bytes;
+}
+
+static irqreturn_t geni_spi_isr(int irq, void *data)
+{
+	struct spi_master *spi = data;
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+	struct geni_se *se = &mas->se;
+	u32 m_irq;
+	unsigned long flags;
+	irqreturn_t ret = IRQ_HANDLED;
+
+	if (mas->cur_mcmd == CMD_NONE)
+		return IRQ_NONE;
+
+	spin_lock_irqsave(&mas->lock, flags);
+	m_irq = readl(se->base + SE_GENI_M_IRQ_STATUS);
+
+	if ((m_irq & M_RX_FIFO_WATERMARK_EN) || (m_irq & M_RX_FIFO_LAST_EN))
+		geni_spi_handle_rx(mas);
+
+	if (m_irq & M_TX_FIFO_WATERMARK_EN)
+		geni_spi_handle_tx(mas);
+
+	if (m_irq & M_CMD_DONE_EN) {
+		if (mas->cur_mcmd == CMD_XFER)
+			spi_finalize_current_transfer(spi);
+		else if (mas->cur_mcmd == CMD_CS)
+			complete(&mas->xfer_done);
+		mas->cur_mcmd = CMD_NONE;
+		/*
+		 * If this happens, then a CMD_DONE came before all the Tx
+		 * buffer bytes were sent out. This is unusual, log this
+		 * condition and disable the WM interrupt to prevent the
+		 * system from stalling due an interrupt storm.
+		 * If this happens when all Rx bytes haven't been received, log
+		 * the condition.
+		 * The only known time this can happen is if bits_per_word != 8
+		 * and some registers that expect xfer lengths in num spi_words
+		 * weren't written correctly.
+		 */
+		if (mas->tx_rem_bytes) {
+			writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
+			dev_err(mas->dev, "Premature done. tx_rem = %d bpw%d\n",
+				mas->tx_rem_bytes, mas->cur_bits_per_word);
+		}
+		if (mas->rx_rem_bytes)
+			dev_err(mas->dev, "Premature done. rx_rem = %d bpw%d\n",
+				mas->rx_rem_bytes, mas->cur_bits_per_word);
+	}
+
+	if ((m_irq & M_CMD_CANCEL_EN) || (m_irq & M_CMD_ABORT_EN)) {
+		mas->cur_mcmd = CMD_NONE;
+		complete(&mas->xfer_done);
+	}
+
+	writel(m_irq, se->base + SE_GENI_M_IRQ_CLEAR);
+	spin_unlock_irqrestore(&mas->lock, flags);
+	return ret;
+}
+
+static int spi_geni_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct spi_master *spi;
+	struct spi_geni_master *mas;
+	struct resource *res;
+	struct geni_se *se;
+
+	spi = spi_alloc_master(&pdev->dev, sizeof(*mas));
+	if (!spi)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, spi);
+	mas = spi_master_get_devdata(spi);
+	mas->dev = &pdev->dev;
+	mas->se.dev = &pdev->dev;
+	mas->se.wrapper = dev_get_drvdata(pdev->dev.parent);
+	se = &mas->se;
+
+	spi->bus_num = -1;
+	spi->dev.of_node = pdev->dev.of_node;
+	mas->se.clk = devm_clk_get(&pdev->dev, "se");
+	if (IS_ERR(mas->se.clk)) {
+		ret = PTR_ERR(mas->se.clk);
+		dev_err(&pdev->dev, "Err getting SE Core clk %d\n", ret);
+		goto spi_geni_probe_err;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	se->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(se->base)) {
+		ret = PTR_ERR(se->base);
+		goto spi_geni_probe_err;
+	}
+
+	spi->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_CS_HIGH;
+	spi->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
+	spi->num_chipselect = 4;
+	spi->max_speed_hz = 50000000;
+	spi->prepare_message = spi_geni_prepare_message;
+	spi->transfer_one = spi_geni_transfer_one;
+	spi->auto_runtime_pm = true;
+	spi->handle_err = handle_fifo_timeout;
+	spi->set_cs = spi_geni_set_cs;
+
+	init_completion(&mas->xfer_done);
+	spin_lock_init(&mas->lock);
+	pm_runtime_enable(&pdev->dev);
+
+	ret = spi_geni_init(mas);
+	if (ret)
+		goto spi_geni_probe_runtime_disable;
+
+	mas->irq = platform_get_irq(pdev, 0);
+	if (mas->irq < 0) {
+		ret = mas->irq;
+		dev_err(&pdev->dev, "Err getting IRQ %d\n", ret);
+		goto spi_geni_probe_runtime_disable;
+	}
+
+	ret = request_irq(mas->irq, geni_spi_isr,
+			IRQF_TRIGGER_HIGH, "spi_geni", spi);
+	if (ret)
+		goto spi_geni_probe_runtime_disable;
+
+	ret = spi_register_master(spi);
+	if (ret)
+		goto spi_geni_probe_free_irq;
+
+	return 0;
+spi_geni_probe_free_irq:
+	free_irq(mas->irq, spi);
+spi_geni_probe_runtime_disable:
+	pm_runtime_disable(&pdev->dev);
+spi_geni_probe_err:
+	spi_master_put(spi);
+	return ret;
+}
+
+static int spi_geni_remove(struct platform_device *pdev)
+{
+	struct spi_master *spi = platform_get_drvdata(pdev);
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+
+	/* Unregister _before_ disabling pm_runtime() so we stop transfers */
+	spi_unregister_master(spi);
+
+	free_irq(mas->irq, spi);
+	pm_runtime_disable(&pdev->dev);
+	return 0;
+}
+
+static int __maybe_unused spi_geni_runtime_suspend(struct device *dev)
+{
+	struct spi_master *spi = dev_get_drvdata(dev);
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+
+	return geni_se_resources_off(&mas->se);
+}
+
+static int __maybe_unused spi_geni_runtime_resume(struct device *dev)
+{
+	struct spi_master *spi = dev_get_drvdata(dev);
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+
+	return geni_se_resources_on(&mas->se);
+}
+
+static int __maybe_unused spi_geni_suspend(struct device *dev)
+{
+	struct spi_master *spi = dev_get_drvdata(dev);
+	int ret;
+
+	ret = spi_master_suspend(spi);
+	if (ret)
+		return ret;
+
+	ret = pm_runtime_force_suspend(dev);
+	if (ret)
+		spi_master_resume(spi);
+
+	return ret;
+}
+
+static int __maybe_unused spi_geni_resume(struct device *dev)
+{
+	struct spi_master *spi = dev_get_drvdata(dev);
+	int ret;
+
+	ret = pm_runtime_force_resume(dev);
+	if (ret)
+		return ret;
+
+	ret = spi_master_resume(spi);
+	if (ret)
+		pm_runtime_force_suspend(dev);
+
+	return ret;
+}
+
+static const struct dev_pm_ops spi_geni_pm_ops = {
+	SET_RUNTIME_PM_OPS(spi_geni_runtime_suspend,
+					spi_geni_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(spi_geni_suspend, spi_geni_resume)
+};
+
+static const struct of_device_id spi_geni_dt_match[] = {
+	{ .compatible = "qcom,geni-spi" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, spi_geni_dt_match);
+
+static struct platform_driver spi_geni_driver = {
+	.probe  = spi_geni_probe,
+	.remove = spi_geni_remove,
+	.driver = {
+		.name = "geni_spi",
+		.pm = &spi_geni_pm_ops,
+		.of_match_table = spi_geni_dt_match,
+	},
+};
+module_platform_driver(spi_geni_driver);
+
+MODULE_DESCRIPTION("SPI driver for GENI based QUP cores");
+MODULE_LICENSE("GPL v2");
-- 
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