[PATCH V3] spi: spi-geni-qcom: Add SPI driver support for GENI based QUP

From: Dilip Kota <dkota@codeaurora.org>
To: swboyd@chromium.org, broonie@kernel.org, mka@chromium.org,
	dianders@chromium.org, linux-kernel@vger.kernel.org,
	linux-spi@vger.kernel.org, Andy Gross <andy.gross@linaro.org>,
	David Brown <david.brown@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org,
	devicetree@vger.kernel.org
Cc: Girish Mahadevan <girishm@codeaurora.org>,
	Dilip Kota <dkota@codeaurora.org>
Subject: [PATCH V3] spi: spi-geni-qcom: Add SPI driver support for GENI based QUP
Date: Fri, 24 Aug 2018 16:12:15 +0530	[thread overview]
Message-ID: <1535107336-2214-1-git-send-email-dkota@codeaurora.org> (raw)

From: Girish Mahadevan <girishm@codeaurora.org>

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@codeaurora.org>
Signed-off-by: Dilip Kota <dkota@codeaurora.org>
---
Addressing all the reviewer commets given in Patchset1.
Summerizing all the comments below:

	MAKEFILE: Arrange SPI-GENI driver in alphabetical order
	Kconfig: Mark SPI_GENI driver dependent on QCOM_GENI_SE
	Enable SPI core auto runtime pm, and remove runtime pm calls.
	Remove spi_geni_unprepare_message(), spi_geni_unprepare_transfer_hardware()
	Remove likely/unlikely keywords.
	Remove get_spi_master() and use dev_get_drvdata()
	Move request_irq to probe()
	Mark bus number assignment to -1 as SPI core framework will assign dynamically
	Use devm_spi_register_master()
	Include platform_device.h instead of of_platform.h
	Removing macros which are used only once:
	        #define SPI_NUM_CHIPSELECT     4
	        #define SPI_XFER_TIMEOUT_MS    250
	Place Register field definitions next to respective Register definitions.
	Replace int and u32 declerations to unsigned int.
	Remove Hex numbers in debug prints.
	Declare mode as u16 in spi_setup_word_len()
	Remove the labels: setup_fifo_params_exit: exit_prepare_transfer_hardware:
	Declaring struct spi_master as spi everywhere in the file.
	Calling spi_finalize_current_transfer() for end of transfer.
	Hard code the SPI controller max frequency instead of reading from DTSI node.
	Spinlock not required, removed it.
	Removed unrequired error prints.
	Fix KASAN error in geni_spi_isr().
	Remove spi-geni-qcom.h
	Remove inter words delay and CS to Clock toggle delay logic in the driver, as of now no clients are using it.
	Will submit this logic in the next patchset.	
	Use major, minor and step macros to read from hardware version register.

 .../devicetree/bindings/soc/qcom/qcom,geni-se.txt  |   2 -
 drivers/spi/Kconfig                                |  12 +
 drivers/spi/Makefile                               |   1 +
 drivers/spi/spi-geni-qcom.c                        | 678 +++++++++++++++++++++
 4 files changed, 691 insertions(+), 2 deletions(-)
 create mode 100644 drivers/spi/spi-geni-qcom.c

diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt
index 68b7d62..16467ed 100644
--- a/Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt
@@ -60,7 +60,6 @@ Required properties:
 - interrupts:		Must contain SPI controller interrupts.
 - clock-names:		Must contain "se".
 - clocks:		Serial engine core clock needed by the device.
-- spi-max-frequency:	Specifies maximum SPI clock frequency, units - Hz.
 - #address-cells:	Must be <1> to define a chip select address on
 			the SPI bus.
 - #size-cells:		Must be <0>.
@@ -112,7 +111,6 @@ Example:
 			pinctrl-names = "default", "sleep";
 			pinctrl-0 = <&qup_1_spi_2_active>;
 			pinctrl-1 = <&qup_1_spi_2_sleep>;
-			spi-max-frequency = <19200000>;
 			#address-cells = <1>;
 			#size-cells = <0>;
 		};
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index ad5d68e..4f7f86f 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 SPI controller with QUP interface"
+	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 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 cb1f437..98337cf 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..5ba0363
--- /dev/null
+++ b/drivers/spi/spi-geni-qcom.c
@@ -0,0 +1,678 @@
+// 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/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>
+
+/* 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)
+
+static irqreturn_t geni_spi_isr(int irq, void *data);
+
+struct spi_geni_master {
+	struct geni_se se;
+	unsigned int irq;
+	struct device *dev;
+	unsigned int rx_fifo_depth;
+	unsigned int tx_fifo_depth;
+	unsigned int tx_fifo_width;
+	unsigned int tx_wm;
+	bool setup;
+	unsigned int cur_speed_hz;
+	unsigned int cur_word_len;
+	unsigned int tx_rem_bytes;
+	unsigned int rx_rem_bytes;
+	struct spi_transfer *cur_xfer;
+	struct completion xfer_done;
+	unsigned int oversampling;
+};
+
+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;
+	struct geni_se *se = &mas->se;
+	int ret;
+
+	ret = geni_se_clk_freq_match(&mas->se,
+				(speed_hz * mas->oversampling), clk_idx,
+				&sclk_freq, true);
+	if (ret) {
+		dev_err(mas->dev, "%s: Failed(%d) to find src clk for %dHz\n",
+						__func__, ret, speed_hz);
+		return ret;
+	}
+
+	*clk_div = ((sclk_freq / mas->oversampling) / speed_hz);
+	if (!(*clk_div)) {
+		dev_err(mas->dev, "%s:Err:sclk:%lu oversampling:%d speed:%u\n",
+			__func__, sclk_freq, mas->oversampling, speed_hz);
+		return -EINVAL;
+	}
+
+	dev_dbg(mas->dev, "%s: req %u sclk %lu, idx %d, div %d\n", __func__,
+				speed_hz, sclk_freq, *clk_idx, *clk_div);
+	ret = clk_set_rate(se->clk, sclk_freq);
+	if (ret)
+		dev_err(mas->dev, "%s: clk_set_rate failed %d\n",
+							__func__, ret);
+	return ret;
+}
+
+static void spi_setup_word_len(struct spi_geni_master *mas, u16 mode,
+					unsigned int bits_per_word)
+{
+	unsigned int word_len, pack_words;
+	bool msb_first = (mode & SPI_LSB_FIRST) ? false : true;
+	struct geni_se *se = &mas->se;
+
+	word_len = readl_relaxed(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->tx_fifo_width % bits_per_word))
+		pack_words = mas->tx_fifo_width / 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_relaxed(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;
+	unsigned int mode = spi_slv->mode;
+	unsigned int loopback_cfg = readl_relaxed(se->base + SE_SPI_LOOPBACK);
+	unsigned int cpol = readl_relaxed(se->base + SE_SPI_CPOL);
+	unsigned int cpha = readl_relaxed(se->base + SE_SPI_CPHA);
+	unsigned int demux_sel, clk_sel, m_clk_cfg, idx, div;
+	int ret = 0;
+	unsigned int demux_output_inv = 0;
+
+	loopback_cfg &= ~LOOPBACK_MSK;
+	cpol &= ~CPOL;
+	cpha &= ~CPHA;
+
+	if (mode & SPI_LOOP)
+		loopback_cfg |= LOOPBACK_ENABLE;
+
+	if (mode & SPI_CPOL)
+		cpol |= CPOL;
+
+	if (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_word_len = 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 %d\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_relaxed(loopback_cfg, se->base + SE_SPI_LOOPBACK);
+	writel_relaxed(demux_sel, se->base + SE_SPI_DEMUX_SEL);
+	writel_relaxed(cpha, se->base + SE_SPI_CPHA);
+	writel_relaxed(cpol, se->base + SE_SPI_CPOL);
+	writel_relaxed(demux_output_inv, se->base + SE_SPI_DEMUX_OUTPUT_INV);
+	writel_relaxed(clk_sel, se->base + SE_GENI_CLK_SEL);
+	writel_relaxed(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 = 0;
+	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, "%s: Couldn't select mode %d", __func__, ret);
+		ret = -EINVAL;
+	}
+	return ret;
+}
+
+static int spi_geni_prepare_transfer_hardware(struct spi_master *spi)
+{
+	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+	struct geni_se *se = &mas->se;
+
+	if (!mas->setup) {
+		unsigned int proto = geni_se_read_proto(se);
+		unsigned int major, minor, step, ver;
+
+		if (proto != GENI_SE_SPI) {
+			dev_err(mas->dev, "Invalid proto %d\n", proto);
+			return -ENXIO;
+		}
+		mas->tx_fifo_depth = geni_se_get_tx_fifo_depth(se);
+		mas->rx_fifo_depth = geni_se_get_rx_fifo_depth(se);
+		mas->tx_fifo_width = 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);
+		mas->oversampling = 1;
+		/* 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);
+		step = GENI_SE_VERSION_STEP(ver);
+
+		if (major == 1 && minor == 0)
+			mas->oversampling = 2;
+		mas->setup = 1;
+	}
+	return 0;
+}
+
+static void setup_fifo_xfer(struct spi_transfer *xfer,
+				struct spi_geni_master *mas, u16 mode,
+				struct spi_master *spi)
+{
+	unsigned int m_cmd = 0;
+	unsigned int m_param = 0;
+	struct geni_se *se = &mas->se;
+	unsigned int spi_tx_cfg = readl_relaxed(se->base + SE_SPI_TRANS_CFG);
+	unsigned int trans_len = 0;
+
+	if (xfer->bits_per_word != mas->cur_word_len) {
+		spi_setup_word_len(mas, mode, xfer->bits_per_word);
+		mas->cur_word_len = xfer->bits_per_word;
+	}
+
+	/* Speed and bits per word can be overridden per transfer */
+	if (xfer->speed_hz != mas->cur_speed_hz) {
+		int ret = 0;
+		unsigned int clk_sel = 0;
+		unsigned int m_clk_cfg = 0;
+		unsigned int idx = 0;
+		unsigned int div = 0;
+
+		ret = get_spi_clk_cfg(xfer->speed_hz, mas, &idx, &div);
+		if (ret) {
+			dev_err(mas->dev, "%s:Err setting clks:%d\n",
+								__func__, 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 consicutive 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_relaxed(clk_sel, se->base + SE_GENI_CLK_SEL);
+		writel_relaxed(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_word_len % MIN_WORD_LEN)) {
+		trans_len =
+			((xfer->len * BITS_PER_BYTE) /
+					mas->cur_word_len) & TRANS_LEN_MSK;
+	} else {
+		unsigned int bytes_per_word =
+			(mas->cur_word_len / BITS_PER_BYTE) + 1;
+
+		trans_len = (xfer->len / bytes_per_word) & TRANS_LEN_MSK;
+	}
+
+	/*
+	 * If CS change flag is set, then toggle the CS line in between
+	 * transfers and keep CS asserted after the last transfer.
+	 * Else if keep CS flag asserted in between transfers and de-assert
+	 * CS after the last message.
+	 */
+	if (xfer->cs_change) {
+		if (list_is_last(&xfer->transfer_list,
+				&spi->cur_msg->transfers))
+			m_param |= FRAGMENTATION;
+	} else {
+		if (!list_is_last(&xfer->transfer_list,
+				&spi->cur_msg->transfers))
+			m_param |= FRAGMENTATION;
+	}
+
+	mas->cur_xfer = xfer;
+	if (m_cmd & SPI_TX_ONLY) {
+		mas->tx_rem_bytes = xfer->len;
+		writel_relaxed(trans_len, se->base + SE_SPI_TX_TRANS_LEN);
+	}
+
+	if (m_cmd & SPI_RX_ONLY) {
+		writel_relaxed(trans_len, se->base + SE_SPI_RX_TRANS_LEN);
+		mas->rx_rem_bytes = xfer->len;
+	}
+	writel_relaxed(spi_tx_cfg, se->base + SE_SPI_TRANS_CFG);
+	geni_se_setup_m_cmd(se, m_cmd, m_param);
+	if (m_cmd & SPI_TX_ONLY)
+		writel_relaxed(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 timeout;
+	struct geni_se *se = &mas->se;
+
+	reinit_completion(&mas->xfer_done);
+	geni_se_cancel_m_cmd(se);
+	writel_relaxed(0, se->base + SE_GENI_TX_WATERMARK_REG);
+	timeout = wait_for_completion_timeout(&mas->xfer_done, HZ);
+	if (!timeout) {
+		reinit_completion(&mas->xfer_done);
+		geni_se_abort_m_cmd(se);
+		timeout = wait_for_completion_timeout(&mas->xfer_done,
+								HZ);
+		if (!timeout)
+			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);
+
+	setup_fifo_xfer(xfer, mas, slv->mode, spi);
+	return 1;
+}
+
+static irqreturn_t geni_spi_handle_tx(struct spi_geni_master *mas)
+{
+	unsigned int i = 0;
+	unsigned int tx_fifo_width = mas->tx_fifo_width / BITS_PER_BYTE;
+	unsigned int max_bytes;
+	const u8 *tx_buf;
+	struct geni_se *se = &mas->se;
+
+	if (!mas->cur_xfer)
+		return IRQ_NONE;
+
+	/*
+	 * For non-byte aligned bits-per-word values(e.g 9).
+	 * The FIFO packing is set to 1 SPI word per FIFO word.
+	 * Assumption is that each SPI word will be accomodated in
+	 * ceil (bits_per_word / bits_per_byte)
+	 * and the next SPI word starts at the next byte.
+	 * In such cases, we can fit 1 SPI word per FIFO word so adjust the
+	 * max byte that can be sent per IRQ accordingly.
+	 */
+	max_bytes = (mas->tx_fifo_depth - mas->tx_wm);
+	if (mas->tx_fifo_width % mas->cur_word_len)
+		max_bytes *= ((mas->cur_word_len / BITS_PER_BYTE) + 1);
+	else
+		max_bytes *= tx_fifo_width;
+	tx_buf = mas->cur_xfer->tx_buf;
+	tx_buf += mas->cur_xfer->len - mas->tx_rem_bytes;
+	if (mas->tx_rem_bytes < max_bytes)
+		max_bytes = mas->tx_rem_bytes;
+	while (i < max_bytes) {
+		unsigned int j;
+		unsigned int fifo_word = 0;
+		u8 *fifo_byte;
+		unsigned int bytes_per_fifo = tx_fifo_width;
+		unsigned int bytes_to_write = 0;
+
+		if (mas->tx_fifo_width % mas->cur_word_len)
+			bytes_per_fifo =
+				(mas->cur_word_len / BITS_PER_BYTE) + 1;
+
+		if (bytes_per_fifo < (max_bytes - i))
+			bytes_to_write = bytes_per_fifo;
+		else
+			bytes_to_write = max_bytes - i;
+
+		fifo_byte = (u8 *)&fifo_word;
+		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_relaxed(0, se->base + SE_GENI_TX_WATERMARK_REG);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t geni_spi_handle_rx(struct spi_geni_master *mas)
+{
+	unsigned int i = 0;
+	struct geni_se *se = &mas->se;
+	unsigned int fifo_width = mas->tx_fifo_width / BITS_PER_BYTE;
+	unsigned int rx_fifo_status;
+	unsigned int rx_bytes = 0;
+	unsigned int rx_wc = 0;
+	u8 *rx_buf;
+
+	if (!mas->cur_xfer)
+		return IRQ_NONE;
+
+	rx_fifo_status = readl_relaxed(se->base + SE_GENI_RX_FIFO_STATUS);
+	rx_buf = mas->cur_xfer->rx_buf;
+	rx_wc = rx_fifo_status & RX_FIFO_WC_MSK;
+	if (rx_fifo_status & RX_LAST) {
+		unsigned int rx_last_byte_valid =
+			(rx_fifo_status & RX_LAST_BYTE_VALID_MSK)
+					>> RX_LAST_BYTE_VALID_SHFT;
+		if (rx_last_byte_valid && (rx_last_byte_valid < 4)) {
+			rx_wc -= 1;
+			rx_bytes += rx_last_byte_valid;
+		}
+	}
+
+	/*
+	 * For non-byte aligned bits-per-word values. (e.g 9)
+	 * The FIFO packing is set to 1 SPI word per FIFO word.
+	 * Assumption is that each SPI word will be accomodated in
+	 * ceil (bits_per_word / bits_per_byte)
+	 * and the next SPI word starts at the next byte.
+	 */
+	if (!(mas->tx_fifo_width % mas->cur_word_len))
+		rx_bytes += rx_wc * fifo_width;
+	else
+		rx_bytes += rx_wc *
+			((mas->cur_word_len / BITS_PER_BYTE) + 1);
+	if (mas->rx_rem_bytes < rx_bytes)
+		rx_bytes = mas->rx_rem_bytes;
+	rx_buf += mas->cur_xfer->len - mas->rx_rem_bytes;
+	while (i < rx_bytes) {
+		unsigned int fifo_word = 0;
+		u8 *fifo_byte;
+		unsigned int bytes_per_fifo = fifo_width;
+		unsigned int read_bytes = 0;
+		unsigned int j;
+
+		if (mas->tx_fifo_width % mas->cur_word_len)
+			bytes_per_fifo =
+				(mas->cur_word_len / BITS_PER_BYTE) + 1;
+		if (bytes_per_fifo < (rx_bytes - i))
+			read_bytes = bytes_per_fifo;
+		else
+			read_bytes = rx_bytes - i;
+		ioread32_rep(se->base + SE_GENI_RX_FIFOn, &fifo_word, 1);
+		fifo_byte = (u8 *)&fifo_word;
+		for (j = 0; j < read_bytes; j++)
+			rx_buf[i++] = fifo_byte[j];
+	}
+	mas->rx_rem_bytes -= rx_bytes;
+	return IRQ_HANDLED;
+}
+
+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;
+	unsigned int m_irq = 0;
+	irqreturn_t ret = IRQ_HANDLED;
+
+	if (pm_runtime_status_suspended(mas->dev)) {
+		ret = IRQ_NONE;
+		goto exit_geni_spi_irq;
+	}
+	m_irq = readl_relaxed(se->base + SE_GENI_M_IRQ_STATUS);
+	if ((m_irq & M_RX_FIFO_WATERMARK_EN) || (m_irq & M_RX_FIFO_LAST_EN))
+		ret = geni_spi_handle_rx(mas);
+
+	if ((m_irq & M_TX_FIFO_WATERMARK_EN))
+		ret = geni_spi_handle_tx(mas);
+
+	if (m_irq & M_CMD_DONE_EN) {
+		spi_finalize_current_transfer(spi);
+		/*
+		 * 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_relaxed(0, se->base + SE_GENI_TX_WATERMARK_REG);
+			dev_err(mas->dev,
+				"%s:Premature Done.tx_rem%d bpw%d\n",
+				__func__, mas->tx_rem_bytes, mas->cur_word_len);
+		}
+		if (mas->rx_rem_bytes)
+			dev_err(mas->dev,
+				"%s:Premature Done.rx_rem%d bpw%d\n",
+				__func__, mas->rx_rem_bytes, mas->cur_word_len);
+	}
+
+	if ((m_irq & M_CMD_CANCEL_EN) || (m_irq & M_CMD_ABORT_EN))
+		complete(&mas->xfer_done);
+exit_geni_spi_irq:
+	writel_relaxed(m_irq, se->base + SE_GENI_M_IRQ_CLEAR);
+	return ret;
+}
+
+static int spi_geni_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct spi_master *spi;
+	struct spi_geni_master *spi_geni;
+	struct resource *res;
+	struct geni_se *se;
+
+	spi = spi_alloc_master(&pdev->dev, sizeof(struct spi_geni_master));
+	if (!spi) {
+		ret = -ENOMEM;
+		goto spi_geni_probe_err;
+	}
+
+	platform_set_drvdata(pdev, spi);
+	spi_geni = spi_master_get_devdata(spi);
+	spi_geni->dev = &pdev->dev;
+	spi_geni->se.dev = &pdev->dev;
+	spi_geni->se.wrapper = dev_get_drvdata(pdev->dev.parent);
+	se = &spi_geni->se;
+
+	spi->bus_num = -1;
+	spi->dev.of_node = pdev->dev.of_node;
+	spi_geni->se.clk = devm_clk_get(&pdev->dev, "se");
+	if (IS_ERR(spi_geni->se.clk)) {
+		ret = PTR_ERR(spi_geni->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 = -ENOMEM;
+		goto spi_geni_probe_err;
+	}
+
+	spi_geni->irq = platform_get_irq(pdev, 0);
+	if (spi_geni->irq < 0) {
+		dev_err(&pdev->dev, "Err getting IRQ\n");
+		ret = spi_geni->irq;
+		goto spi_geni_probe_unmap;
+	}
+	ret = devm_request_irq(&pdev->dev, spi_geni->irq, geni_spi_isr,
+				IRQF_TRIGGER_HIGH, "spi_geni", spi);
+	if (ret)
+		goto spi_geni_probe_unmap;
+
+	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_transfer_hardware = spi_geni_prepare_transfer_hardware;
+	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;
+
+	init_completion(&spi_geni->xfer_done);
+	pm_runtime_enable(&pdev->dev);
+	ret = devm_spi_register_master(&pdev->dev, spi);
+	if (ret)
+		goto spi_geni_probe_unmap;
+
+	return ret;
+spi_geni_probe_unmap:
+	devm_iounmap(&pdev->dev, se->base);
+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 *spi_geni = spi_master_get_devdata(spi);
+
+	geni_se_resources_off(&spi_geni->se);
+	pm_runtime_put_noidle(&pdev->dev);
+	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 *spi_geni = spi_master_get_devdata(spi);
+
+	return geni_se_resources_off(&spi_geni->se);
+}
+
+static int __maybe_unused spi_geni_runtime_resume(struct device *dev)
+{
+	struct spi_master *spi = dev_get_drvdata(dev);
+	struct spi_geni_master *spi_geni = spi_master_get_devdata(spi);
+
+	return geni_se_resources_on(&spi_geni->se);
+}
+
+static int __maybe_unused spi_geni_suspend(struct device *dev)
+{
+	if (!pm_runtime_status_suspended(dev))
+		return -EBUSY;
+	return 0;
+}
+
+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, NULL)
+};
+
+static const struct of_device_id spi_geni_dt_match[] = {
+	{ .compatible = "qcom,geni-spi" },
+	{}
+};
+
+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");
-- 
Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

