[PATCH 1/6 v5] serial: qcom: add support for GENI serial driver

[Dzmitry Sankouski <dsankouski@gmail.com>]

Generic Interface (GENI) Serial Engine (SE) based uart
can be found on newer qualcomm SOCs, starting from SDM845.
Tested on Samsung SM-G9600(starqltechn)
by chain-loading u-boot with stock bootloader.

Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com>
Cc: Ramon Fried <rfried.dev@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
---
Changes for v2:
- change functions return type to void, where possible
- remove '.' from summary line
Changes for v3:
- move function open brace on new line
- use tab between define name and value
- define: wrap expression with braces, remove braces from constants
Changes for v4:
- add linux/delay.h header
Changes for v5:
- Kconfig: break long lines
- rearrange definitions
- add docs to functions
- add docs on cfg0 variable (packing configuration info)
- get_clk_div_rate, get_clk_cfg: use mainline linux function instead of
starqltechn downstream version
- use setbits_le32
- extract qcom_geni_serial_abort_rx function
- remove explicit pinctrl setup
- make an unconditional cancel at serial init
- calculate CLK_DIV on host machine with #define, when debug enabled.
    throw error, if we cannot get target baudrate with CONFIG_DEBUG_UART_CLOCK
    value. This is because we cannot adjust clocks at early debug.

 MAINTAINERS                                   |   1 +
 .../serial/msm-geni-serial.txt                |   6 +
 drivers/serial/Kconfig                        |  18 +
 drivers/serial/Makefile                       |   1 +
 drivers/serial/serial_msm_geni.c              | 613 ++++++++++++++++++
 5 files changed, 639 insertions(+)
 create mode 100644 doc/device-tree-bindings/serial/msm-geni-serial.txt
 create mode 100644 drivers/serial/serial_msm_geni.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 776ff703b9..52ddc99cda 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -390,6 +390,7 @@ F:	drivers/gpio/msm_gpio.c
 F:	drivers/mmc/msm_sdhci.c
 F:	drivers/phy/msm8916-usbh-phy.c
 F:	drivers/serial/serial_msm.c
+F:	drivers/serial/serial_msm_geni.c
 F:	drivers/smem/msm_smem.c
 F:	drivers/usb/host/ehci-msm.c
 
diff --git a/doc/device-tree-bindings/serial/msm-geni-serial.txt b/doc/device-tree-bindings/serial/msm-geni-serial.txt
new file mode 100644
index 0000000000..9eadc2561b
--- /dev/null
+++ b/doc/device-tree-bindings/serial/msm-geni-serial.txt
@@ -0,0 +1,6 @@
+Qualcomm GENI UART
+
+Required properties:
+- compatible: must be "qcom,msm-geni-uart"
+- reg: start address and size of the registers
+- clock: interface clock (must accept baudrate as a frequency)
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 93348c0929..5d9d4b46f2 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -278,6 +278,14 @@ config DEBUG_UART_S5P
 	  will need to provide parameters to make this work. The driver will
 	  be available until the real driver-model serial is running.
 
+config DEBUG_UART_MSM_GENI
+	bool "Qualcomm snapdragon"
+	depends on ARCH_SNAPDRAGON
+	help
+	  Select this to enable a debug UART using the serial_msm driver. You
+	  will need to provide parameters to make this work. The driver will
+	  be available until the real driver-model serial is running.
+
 config DEBUG_UART_MESON
 	bool "Amlogic Meson"
 	depends on MESON_SERIAL
@@ -783,6 +791,16 @@ config MSM_SERIAL
 	  for example APQ8016 and MSM8916.
 	  Single baudrate is supported in current implementation (115200).
 
+config MSM_GENI_SERIAL
+	bool "Qualcomm on-chip GENI UART"
+	help
+	  Support UART based on Generic Interface (GENI) Serial Engine (SE),
+	  used on Qualcomm Snapdragon SoCs. Should support all qualcomm SOCs
+	  with Qualcomm Universal Peripheral (QUP) Wrapper cores,
+	  i.e. newer ones, starting from SDM845.
+	  Driver works in FIFO mode.
+	  Multiple baudrates supported.
+
 config OCTEON_SERIAL_BOOTCMD
 	bool "MIPS Octeon PCI remote bootcmd input"
 	depends on ARCH_OCTEON
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 3cbea8156f..d44caf4ea2 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_PIC32_SERIAL) += serial_pic32.o
 obj-$(CONFIG_BCM283X_MU_SERIAL) += serial_bcm283x_mu.o
 obj-$(CONFIG_BCM283X_PL011_SERIAL) += serial_bcm283x_pl011.o
 obj-$(CONFIG_MSM_SERIAL) += serial_msm.o
+obj-$(CONFIG_MSM_GENI_SERIAL) += serial_msm_geni.o
 obj-$(CONFIG_MVEBU_A3700_UART) += serial_mvebu_a3700.o
 obj-$(CONFIG_MPC8XX_CONS) += serial_mpc8xx.o
 obj-$(CONFIG_NULLDEV_SERIAL) += serial_nulldev.o
diff --git a/drivers/serial/serial_msm_geni.c b/drivers/serial/serial_msm_geni.c
new file mode 100644
index 0000000000..3e255a99dc
--- /dev/null
+++ b/drivers/serial/serial_msm_geni.c
@@ -0,0 +1,613 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Qualcomm GENI serial engine UART driver
+ *
+ * (C) Copyright 2021 Dzmitry Sankouski <dsankouski@gmail.com>
+ *
+ * Based on Linux driver.
+ */
+
+#include <asm/io.h>
+#include <clk.h>
+#include <common.h>
+#include <dm.h>
+#include <dm/pinctrl.h>
+#include <errno.h>
+#include <linux/compiler.h>
+#include <log.h>
+#include <linux/delay.h>
+#include <malloc.h>
+#include <serial.h>
+#include <watchdog.h>
+#include <linux/bug.h>
+
+#define UART_OVERSAMPLING	32
+#define STALE_TIMEOUT	160
+
+#define USEC_PER_SEC	1000000L
+
+/* Registers*/
+#define GENI_FORCE_DEFAULT_REG	0x20
+#define GENI_SER_M_CLK_CFG	0x48
+#define GENI_SER_S_CLK_CFG	0x4C
+#define SE_HW_PARAM_0	0xE24
+#define SE_GENI_STATUS	0x40
+#define SE_GENI_S_CMD0	0x630
+#define SE_GENI_S_CMD_CTRL_REG	0x634
+#define SE_GENI_S_IRQ_CLEAR	0x648
+#define SE_GENI_S_IRQ_STATUS	0x640
+#define SE_GENI_S_IRQ_EN	0x644
+#define SE_GENI_M_CMD0	0x600
+#define SE_GENI_M_CMD_CTRL_REG	0x604
+#define SE_GENI_M_IRQ_CLEAR	0x618
+#define SE_GENI_M_IRQ_STATUS	0x610
+#define SE_GENI_M_IRQ_EN	0x614
+#define SE_GENI_TX_FIFOn	0x700
+#define SE_GENI_RX_FIFOn	0x780
+#define SE_GENI_TX_FIFO_STATUS	0x800
+#define SE_GENI_RX_FIFO_STATUS	0x804
+#define SE_GENI_TX_WATERMARK_REG	0x80C
+#define SE_GENI_TX_PACKING_CFG0	0x260
+#define SE_GENI_TX_PACKING_CFG1	0x264
+#define SE_GENI_RX_PACKING_CFG0	0x284
+#define SE_GENI_RX_PACKING_CFG1	0x288
+#define SE_UART_RX_STALE_CNT	0x294
+#define SE_UART_TX_TRANS_LEN	0x270
+#define SE_UART_TX_STOP_BIT_LEN	0x26c
+#define SE_UART_TX_WORD_LEN	0x268
+#define SE_UART_RX_WORD_LEN	0x28c
+#define SE_UART_TX_TRANS_CFG	0x25c
+#define SE_UART_TX_PARITY_CFG	0x2a4
+#define SE_UART_RX_TRANS_CFG	0x280
+#define SE_UART_RX_PARITY_CFG	0x2a8
+
+#define M_TX_FIFO_WATERMARK_EN	(BIT(30))
+#define DEF_TX_WM	2
+/* GENI_FORCE_DEFAULT_REG fields */
+#define FORCE_DEFAULT	(BIT(0))
+
+#define S_CMD_ABORT_EN	(BIT(5))
+
+#define UART_START_READ	0x1
+
+/* GENI_M_CMD_CTRL_REG */
+#define M_GENI_CMD_CANCEL	(BIT(2))
+#define M_GENI_CMD_ABORT	(BIT(1))
+#define M_GENI_DISABLE	(BIT(0))
+
+#define M_CMD_ABORT_EN	(BIT(5))
+#define M_CMD_DONE_EN	(BIT(0))
+#define M_CMD_DONE_DISABLE_MASK	(~M_CMD_DONE_EN)
+
+#define S_GENI_CMD_ABORT	(BIT(1))
+
+/* GENI_S_CMD0 fields */
+#define S_OPCODE_MSK	(GENMASK(31, 27))
+#define S_PARAMS_MSK	(GENMASK(26, 0))
+
+/* GENI_STATUS fields */
+#define M_GENI_CMD_ACTIVE	(BIT(0))
+#define S_GENI_CMD_ACTIVE	(BIT(12))
+#define M_CMD_DONE_EN	(BIT(0))
+#define S_CMD_DONE_EN	(BIT(0))
+
+#define M_OPCODE_SHIFT	27
+#define S_OPCODE_SHIFT	27
+#define M_TX_FIFO_WATERMARK_EN	(BIT(30))
+#define UART_START_TX	0x1
+#define UART_CTS_MASK	(BIT(1))
+#define M_SEC_IRQ_EN	(BIT(31))
+#define TX_FIFO_WC_MSK	(GENMASK(27, 0))
+#define RX_FIFO_WC_MSK	(GENMASK(24, 0))
+
+#define S_RX_FIFO_WATERMARK_EN	(BIT(26))
+#define S_RX_FIFO_LAST_EN	(BIT(27))
+#define M_RX_FIFO_WATERMARK_EN	(BIT(26))
+#define M_RX_FIFO_LAST_EN	(BIT(27))
+
+/* GENI_SER_M_CLK_CFG/GENI_SER_S_CLK_CFG */
+#define SER_CLK_EN	(BIT(0))
+#define CLK_DIV_MSK	(GENMASK(15, 4))
+#define CLK_DIV_SHFT	4
+
+/* SE_HW_PARAM_0 fields */
+#define TX_FIFO_WIDTH_MSK	(GENMASK(29, 24))
+#define TX_FIFO_WIDTH_SHFT	24
+#define TX_FIFO_DEPTH_MSK	(GENMASK(21, 16))
+#define TX_FIFO_DEPTH_SHFT	16
+
+/*
+ * Predefined packing configuration of the serial engine (CFG0, CFG1 regs)
+ * for uart mode.
+ *
+ * Defines following configuration:
+ * - Bits of data per transfer word             8
+ * - Number of words per fifo element           4
+ * - Transfer from MSB to LSB or vice-versa     false
+ */
+#define UART_PACKING_CFG0   0xf
+#define UART_PACKING_CFG1   0x0
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct msm_serial_data {
+	phys_addr_t base;
+	u32 baud;
+};
+
+unsigned long root_freq[] = {7372800,  14745600, 19200000, 29491200,
+					 32000000, 48000000, 64000000, 80000000,
+					 96000000, 100000000};
+
+/**
+ * get_clk_cfg() - Get clock rate to apply on clock supplier.
+ * @clk_freq:	Desired clock frequency after build-in divider.
+ *
+ * Return: frequency, supported by clock supplier, multiple of clk_freq.
+ */
+static int get_clk_cfg(unsigned long clk_freq)
+{
+	for (int i = 0; i < ARRAY_SIZE(root_freq); i++) {
+		if (!(root_freq[i] % clk_freq))
+			return root_freq[i];
+	}
+	return 0;
+}
+
+/**
+ * get_clk_div_rate() - Find clock supplier frequency, and calculate divisor.
+ * @baud:	        Baudrate.
+ * @sampling_rate:	Clock ticks per character.
+ * @clk_div:	    Pointer to calculated divisor.
+ *
+ * This function searches for suitable frequency for clock supplier,
+ * calculates divisor for internal divider, based on found frequency,
+ * and stores divisor under clk_div pointer.
+ *
+ * Return: frequency, supported by clock supplier, multiple of clk_freq.
+ */
+static int get_clk_div_rate(u32 baud,
+							u64 sampling_rate, u32 *clk_div)
+{
+	unsigned long ser_clk;
+	unsigned long desired_clk;
+
+	desired_clk = baud * sampling_rate;
+	ser_clk = get_clk_cfg(desired_clk);
+	if (!ser_clk) {
+		pr_err("%s: Can't find matching DFS entry for baud %d\n",
+								__func__, baud);
+		return ser_clk;
+	}
+
+	*clk_div = ser_clk / desired_clk;
+	return ser_clk;
+}
+
+static int geni_serial_set_clock_rate(struct udevice *dev, u64 rate)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = devm_clk_get(dev, "se-clk");
+	if (!clk)
+		return -EINVAL;
+
+	ret = clk_set_rate(clk, rate);
+	return ret;
+}
+
+/**
+ * geni_se_get_tx_fifo_depth() - Get the TX fifo depth of the serial engine
+ * @base:	Pointer to the concerned serial engine.
+ *
+ * This function is used to get the depth i.e. number of elements in the
+ * TX fifo of the serial engine.
+ *
+ * Return: TX fifo depth in units of FIFO words.
+ */
+static inline u32 geni_se_get_tx_fifo_depth(long base)
+{
+	u32 tx_fifo_depth;
+
+	tx_fifo_depth = ((readl(base + SE_HW_PARAM_0) & TX_FIFO_DEPTH_MSK) >>
+			 TX_FIFO_DEPTH_SHFT);
+	return tx_fifo_depth;
+}
+
+/**
+ * geni_se_get_tx_fifo_width() - Get the TX fifo width of the serial engine
+ * @base:	Pointer to the concerned serial engine.
+ *
+ * This function is used to get the width i.e. word size per element in the
+ * TX fifo of the serial engine.
+ *
+ * Return: TX fifo width in bits
+ */
+static inline u32 geni_se_get_tx_fifo_width(long base)
+{
+	u32 tx_fifo_width;
+
+	tx_fifo_width = ((readl(base + SE_HW_PARAM_0) & TX_FIFO_WIDTH_MSK) >>
+			 TX_FIFO_WIDTH_SHFT);
+	return tx_fifo_width;
+}
+
+static inline void geni_serial_baud(phys_addr_t base_address, u32 clk_div,
+									int baud)
+{
+	u32 s_clk_cfg = 0;
+
+	s_clk_cfg |= SER_CLK_EN;
+	s_clk_cfg |= (clk_div << CLK_DIV_SHFT);
+
+	writel(s_clk_cfg, base_address + GENI_SER_M_CLK_CFG);
+	writel(s_clk_cfg, base_address + GENI_SER_S_CLK_CFG);
+}
+
+int msm_serial_setbrg(struct udevice *dev, int baud)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+
+	priv->baud = baud;
+	u32 clk_div;
+	u64 clk_rate;
+
+	clk_rate = get_clk_div_rate(baud, UART_OVERSAMPLING, &clk_div);
+	geni_serial_set_clock_rate(dev, clk_rate);
+	geni_serial_baud(priv->base, clk_div, baud);
+
+	return 0;
+}
+
+/**
+ * qcom_geni_serial_poll_bit() - Poll reg bit until desired value or timeout.
+ * @base:	Pointer to the concerned serial engine.
+ * @offset:	Offset to register address.
+ * @field:	AND bitmask for desired bit.
+ * @set:	Desired bit value.
+ *
+ * This function is used to get the width i.e. word size per element in the
+ * TX fifo of the serial engine.
+ *
+ * Return: true, when register bit equals desired value, false, when timeout
+ * reached.
+ */
+static bool qcom_geni_serial_poll_bit(const struct udevice *dev, int offset,
+					  int field, bool set)
+{
+	u32 reg;
+	struct msm_serial_data *priv = dev_get_priv(dev);
+	unsigned int baud;
+	unsigned int tx_fifo_depth;
+	unsigned int tx_fifo_width;
+	unsigned int fifo_bits;
+	unsigned long timeout_us = 10000;
+
+	baud = 115200;
+
+	if (priv) {
+		baud = priv->baud;
+		if (!baud)
+			baud = 115200;
+		tx_fifo_depth = geni_se_get_tx_fifo_depth(priv->base);
+		tx_fifo_width = geni_se_get_tx_fifo_width(priv->base);
+		fifo_bits = tx_fifo_depth * tx_fifo_width;
+		/*
+		 * Total polling iterations based on FIFO worth of bytes to be
+		 * sent at current baud. Add a little fluff to the wait.
+		 */
+		timeout_us = ((fifo_bits * USEC_PER_SEC) / baud) + 500;
+	}
+
+	timeout_us = DIV_ROUND_UP(timeout_us, 10) * 10;
+	while (timeout_us) {
+		reg = readl(priv->base + offset);
+		if ((bool)(reg & field) == set)
+			return true;
+		udelay(10);
+		timeout_us -= 10;
+	}
+	return false;
+}
+
+static void qcom_geni_serial_setup_tx(u64 base, u32 xmit_size)
+{
+	u32 m_cmd;
+
+	writel(xmit_size, base + SE_UART_TX_TRANS_LEN);
+	m_cmd = UART_START_TX << M_OPCODE_SHIFT;
+	writel(m_cmd, base + SE_GENI_M_CMD0);
+}
+
+static inline void qcom_geni_serial_poll_tx_done(const struct udevice *dev)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+	int done = 0;
+	u32 irq_clear = M_CMD_DONE_EN;
+
+	done = qcom_geni_serial_poll_bit(dev, SE_GENI_M_IRQ_STATUS,
+					 M_CMD_DONE_EN, true);
+	if (!done) {
+		writel(M_GENI_CMD_ABORT, priv->base + SE_GENI_M_CMD_CTRL_REG);
+		irq_clear |= M_CMD_ABORT_EN;
+		qcom_geni_serial_poll_bit(dev, SE_GENI_M_IRQ_STATUS,
+					  M_CMD_ABORT_EN, true);
+	}
+	writel(irq_clear, priv->base + SE_GENI_M_IRQ_CLEAR);
+}
+
+static u32 qcom_geni_serial_tx_empty(u64 base)
+{
+	return !readl(base + SE_GENI_TX_FIFO_STATUS);
+}
+
+/**
+ * geni_se_setup_s_cmd() - Setup the secondary sequencer
+ * @se:		Pointer to the concerned serial engine.
+ * @cmd:	Command/Operation to setup in the secondary sequencer.
+ * @params:	Parameter for the sequencer command.
+ *
+ * This function is used to configure the secondary sequencer with the
+ * command and its associated parameters.
+ */
+static inline void geni_se_setup_s_cmd(u64 base, u32 cmd, u32 params)
+{
+	u32 s_cmd;
+
+	s_cmd = readl(base + SE_GENI_S_CMD0);
+	s_cmd &= ~(S_OPCODE_MSK | S_PARAMS_MSK);
+	s_cmd |= (cmd << S_OPCODE_SHIFT);
+	s_cmd |= (params & S_PARAMS_MSK);
+	writel(s_cmd, base + SE_GENI_S_CMD0);
+}
+
+static void qcom_geni_serial_start_tx(u64 base)
+{
+	u32 irq_en;
+	u32 status;
+
+	status = readl(base + SE_GENI_STATUS);
+	if (status & M_GENI_CMD_ACTIVE)
+		return;
+
+	if (!qcom_geni_serial_tx_empty(base))
+		return;
+
+	irq_en = readl(base + SE_GENI_M_IRQ_EN);
+	irq_en |= M_TX_FIFO_WATERMARK_EN | M_CMD_DONE_EN;
+
+	writel(DEF_TX_WM, base + SE_GENI_TX_WATERMARK_REG);
+	writel(irq_en, base + SE_GENI_M_IRQ_EN);
+}
+
+static void qcom_geni_serial_start_rx(struct udevice *dev)
+{
+	u32 status;
+	struct msm_serial_data *priv = dev_get_priv(dev);
+
+	status = readl(priv->base + SE_GENI_STATUS);
+
+	geni_se_setup_s_cmd(priv->base, UART_START_READ, 0);
+
+	setbits_le32(priv->base + SE_GENI_S_IRQ_EN, S_RX_FIFO_WATERMARK_EN | S_RX_FIFO_LAST_EN);
+	setbits_le32(priv->base + SE_GENI_M_IRQ_EN, M_RX_FIFO_WATERMARK_EN | M_RX_FIFO_LAST_EN);
+}
+
+static void qcom_geni_serial_abort_rx(struct udevice *dev)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+
+	u32 irq_clear = S_CMD_DONE_EN | S_CMD_ABORT_EN;
+
+	writel(S_GENI_CMD_ABORT, priv->base + SE_GENI_S_CMD_CTRL_REG);
+	qcom_geni_serial_poll_bit(dev, SE_GENI_S_CMD_CTRL_REG,
+					S_GENI_CMD_ABORT, false);
+	writel(irq_clear, priv->base + SE_GENI_S_IRQ_CLEAR);
+	writel(FORCE_DEFAULT, priv->base + GENI_FORCE_DEFAULT_REG);
+}
+
+static void msm_geni_serial_setup_rx(struct udevice *dev)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+
+	qcom_geni_serial_abort_rx(dev);
+
+	writel(UART_PACKING_CFG0, priv->base + SE_GENI_RX_PACKING_CFG0);
+	writel(UART_PACKING_CFG1, priv->base + SE_GENI_RX_PACKING_CFG1);
+
+	geni_se_setup_s_cmd(priv->base, UART_START_READ, 0);
+
+	setbits_le32(priv->base + SE_GENI_S_IRQ_EN, S_RX_FIFO_WATERMARK_EN | S_RX_FIFO_LAST_EN);
+	setbits_le32(priv->base + SE_GENI_M_IRQ_EN, M_RX_FIFO_WATERMARK_EN | M_RX_FIFO_LAST_EN);
+}
+
+static int msm_serial_putc(struct udevice *dev, const char ch)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+
+	writel(DEF_TX_WM, priv->base + SE_GENI_TX_WATERMARK_REG);
+	qcom_geni_serial_setup_tx(priv->base, 1);
+
+	qcom_geni_serial_poll_bit(dev, SE_GENI_M_IRQ_STATUS,
+				  M_TX_FIFO_WATERMARK_EN, true);
+
+	writel(ch, priv->base + SE_GENI_TX_FIFOn);
+	writel(M_TX_FIFO_WATERMARK_EN, priv->base + SE_GENI_M_IRQ_CLEAR);
+
+	qcom_geni_serial_poll_tx_done(dev);
+
+	return 0;
+}
+
+static int msm_serial_getc(struct udevice *dev)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+	u32 rx_fifo;
+	u32 m_irq_status;
+	u32 s_irq_status;
+
+	writel(1 << S_OPCODE_SHIFT, priv->base + SE_GENI_S_CMD0);
+
+	qcom_geni_serial_poll_bit(dev, SE_GENI_M_IRQ_STATUS, M_SEC_IRQ_EN,
+				  true);
+
+	m_irq_status = readl(priv->base + SE_GENI_M_IRQ_STATUS);
+	s_irq_status = readl(priv->base + SE_GENI_S_IRQ_STATUS);
+	writel(m_irq_status, priv->base + SE_GENI_M_IRQ_CLEAR);
+	writel(s_irq_status, priv->base + SE_GENI_S_IRQ_CLEAR);
+	qcom_geni_serial_poll_bit(dev, SE_GENI_RX_FIFO_STATUS, RX_FIFO_WC_MSK,
+				  true);
+
+	if (!readl(priv->base + SE_GENI_RX_FIFO_STATUS))
+		return 0;
+
+	rx_fifo = readl(priv->base + SE_GENI_RX_FIFOn);
+	return rx_fifo & 0xff;
+}
+
+static int msm_serial_pending(struct udevice *dev, bool input)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+
+	if (input)
+		return readl(priv->base + SE_GENI_RX_FIFO_STATUS) &
+			   RX_FIFO_WC_MSK;
+	else
+		return readl(priv->base + SE_GENI_TX_FIFO_STATUS) &
+			   TX_FIFO_WC_MSK;
+
+	return 0;
+}
+
+static const struct dm_serial_ops msm_serial_ops = {
+	.putc = msm_serial_putc,
+	.pending = msm_serial_pending,
+	.getc = msm_serial_getc,
+	.setbrg = msm_serial_setbrg,
+};
+
+static inline void geni_serial_init(struct udevice *dev)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+	phys_addr_t base_address = priv->base;
+	u32 tx_trans_cfg;
+	u32 tx_parity_cfg = 0; /* Disable Tx Parity */
+	u32 rx_trans_cfg = 0;
+	u32 rx_parity_cfg = 0; /* Disable Rx Parity */
+	u32 stop_bit_len = 0;  /* Default stop bit length - 1 bit */
+	u32 bits_per_char;
+
+	/*
+	 * Ignore Flow control.
+	 * n = 8.
+	 */
+	tx_trans_cfg = UART_CTS_MASK;
+	bits_per_char = BITS_PER_BYTE;
+
+	/*
+	 * Make an unconditional cancel on the main sequencer to reset
+	 * it else we could end up in data loss scenarios.
+	 */
+	qcom_geni_serial_poll_tx_done(dev);
+	qcom_geni_serial_abort_rx(dev);
+
+	writel(UART_PACKING_CFG0, base_address + SE_GENI_TX_PACKING_CFG0);
+	writel(UART_PACKING_CFG1, base_address + SE_GENI_TX_PACKING_CFG1);
+	writel(UART_PACKING_CFG0, base_address + SE_GENI_RX_PACKING_CFG0);
+	writel(UART_PACKING_CFG1, base_address + SE_GENI_RX_PACKING_CFG1);
+
+	writel(tx_trans_cfg, base_address + SE_UART_TX_TRANS_CFG);
+	writel(tx_parity_cfg, base_address + SE_UART_TX_PARITY_CFG);
+	writel(rx_trans_cfg, base_address + SE_UART_RX_TRANS_CFG);
+	writel(rx_parity_cfg, base_address + SE_UART_RX_PARITY_CFG);
+	writel(bits_per_char, base_address + SE_UART_TX_WORD_LEN);
+	writel(bits_per_char, base_address + SE_UART_RX_WORD_LEN);
+	writel(stop_bit_len, base_address + SE_UART_TX_STOP_BIT_LEN);
+}
+
+static int msm_serial_probe(struct udevice *dev)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+
+	/* No need to reinitialize the UART after relocation */
+	if (gd->flags & GD_FLG_RELOC)
+		return 0;
+
+	geni_serial_init(dev);
+	msm_geni_serial_setup_rx(dev);
+	qcom_geni_serial_start_rx(dev);
+	qcom_geni_serial_start_tx(priv->base);
+
+	return 0;
+}
+
+static int msm_serial_ofdata_to_platdata(struct udevice *dev)
+{
+	struct msm_serial_data *priv = dev_get_priv(dev);
+
+	priv->base = dev_read_addr(dev);
+	if (priv->base == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct udevice_id msm_serial_ids[] = {
+	{.compatible = "qcom,msm-geni-uart"}, {}};
+
+U_BOOT_DRIVER(serial_msm_geni) = {
+	.name = "serial_msm_geni",
+	.id = UCLASS_SERIAL,
+	.of_match = msm_serial_ids,
+	.of_to_plat = msm_serial_ofdata_to_platdata,
+	.priv_auto = sizeof(struct msm_serial_data),
+	.probe = msm_serial_probe,
+	.ops = &msm_serial_ops,
+};
+
+#ifdef CONFIG_DEBUG_UART_MSM_GENI
+
+static struct msm_serial_data init_serial_data = {
+	.base = CONFIG_DEBUG_UART_BASE
+};
+
+/* Serial dumb device, to reuse driver code */
+static struct udevice init_dev = {
+	.priv_ = &init_serial_data,
+};
+
+#include <debug_uart.h>
+
+#define CLK_DIV (CONFIG_DEBUG_UART_CLOCK / \
+					(CONFIG_BAUDRATE * UART_OVERSAMPLING))
+#if (CONFIG_DEBUG_UART_CLOCK % (CONFIG_BAUDRATE * UART_OVERSAMPLING) > 0)
+#error Clocks cannot be set at early debug. Change CONFIG_BAUDRATE
+#endif
+
+static inline void _debug_uart_init(void)
+{
+	phys_addr_t base = CONFIG_DEBUG_UART_BASE;
+
+	geni_serial_init(&init_dev);
+	geni_serial_baud(base, CLK_DIV, CONFIG_BAUDRATE);
+	qcom_geni_serial_start_tx(base);
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+	phys_addr_t base = CONFIG_DEBUG_UART_BASE;
+
+	writel(DEF_TX_WM, base + SE_GENI_TX_WATERMARK_REG);
+	qcom_geni_serial_setup_tx(base, 1);
+	qcom_geni_serial_poll_bit(&init_dev, SE_GENI_M_IRQ_STATUS,
+				  M_TX_FIFO_WATERMARK_EN, true);
+
+	writel(ch, base + SE_GENI_TX_FIFOn);
+	writel(M_TX_FIFO_WATERMARK_EN, base + SE_GENI_M_IRQ_CLEAR);
+	qcom_geni_serial_poll_tx_done(&init_dev);
+}
+
+DEBUG_UART_FUNCS
+
+#endif
-- 
2.20.1