libpayload: Add UART for qcs405

TEST=build

Change-Id: I43164cf9eacc844af1d048f7b6ebbda96fc9d202
Signed-off-by: Prudhvi Yarlagadda <pyarlaga@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Nitheesh Sekar <nsekar@codeaurora.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/29957
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

2 files changed, 556 insertions, 0 deletions

diff --git a/payloads/libpayload/drivers/Makefile.inc b/payloads/libpayload/drivers/Makefile.inc
index 40e587c223..b4e75943f3 100644
--- a/payloads/libpayload/drivers/Makefile.inc
+++ b/payloads/libpayload/drivers/Makefile.inc
@@ -37,6 +37,7 @@ libc-$(CONFIG_LP_8250_SERIAL_CONSOLE) += serial/8250.c serial/serial.c
 libc-$(CONFIG_LP_S5P_SERIAL_CONSOLE) += serial/s5p.c serial/serial.c
 libc-$(CONFIG_LP_IPQ806X_SERIAL_CONSOLE) += serial/ipq806x.c serial/serial.c
 libc-$(CONFIG_LP_IPQ40XX_SERIAL_CONSOLE) += serial/ipq40xx.c serial/serial.c
+libc-$(CONFIG_LP_QCS405_SERIAL_CONSOLE) += serial/qcs405.c serial/serial.c
 libc-$(CONFIG_LP_PC_KEYBOARD) += i8042/keyboard.c
 libc-$(CONFIG_LP_PC_MOUSE) += i8042/mouse.c
 libc-$(CONFIG_LP_PC_I8042) += i8042/i8042.c
diff --git a/payloads/libpayload/drivers/serial/qcs405.c b/payloads/libpayload/drivers/serial/qcs405.c
new file mode 100644
index 0000000000..9f02e17263
--- /dev/null
+++ b/payloads/libpayload/drivers/serial/qcs405.c
@@ -0,0 +1,555 @@
+/*
+ * Copyright (c) 2010-2012, 2014, 2016, 2019, The Linux Foundation.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ *       copyright notice, this list of conditions and the following
+ *       disclaimer in the documentation and/or other materials provided
+ *       with the distribution.
+ *     * Neither the name of The Linux Foundation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+ * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <libpayload.h>
+
+#define UART_DM_CLK_RX_TX_BIT_RATE 0xFF
+
+enum MSM_BOOT_UART_DM_PARITY_MODE {
+	MSM_BOOT_UART_DM_NO_PARITY,
+	MSM_BOOT_UART_DM_ODD_PARITY,
+	MSM_BOOT_UART_DM_EVEN_PARITY,
+	MSM_BOOT_UART_DM_SPACE_PARITY
+};
+
+/* UART Stop Bit Length */
+enum MSM_BOOT_UART_DM_STOP_BIT_LEN {
+	MSM_BOOT_UART_DM_SBL_9_16,
+	MSM_BOOT_UART_DM_SBL_1,
+	MSM_BOOT_UART_DM_SBL_1_9_16,
+	MSM_BOOT_UART_DM_SBL_2
+};
+
+/* UART Bits per Char */
+enum MSM_BOOT_UART_DM_BITS_PER_CHAR {
+	MSM_BOOT_UART_DM_5_BPS,
+	MSM_BOOT_UART_DM_6_BPS,
+	MSM_BOOT_UART_DM_7_BPS,
+	MSM_BOOT_UART_DM_8_BPS
+};
+
+/* 8-N-1 Configuration */
+#define MSM_BOOT_UART_DM_8_N_1_MODE	(MSM_BOOT_UART_DM_NO_PARITY | \
+					 (MSM_BOOT_UART_DM_SBL_1 << 2) | \
+					 (MSM_BOOT_UART_DM_8_BPS << 4))
+
+/* UART_DM Registers */
+
+/* UART Operational Mode Register */
+#define MSM_BOOT_UART_DM_MR1(base)		((base) + 0x00)
+#define MSM_BOOT_UART_DM_MR2(base)		((base) + 0x04)
+#define MSM_BOOT_UART_DM_RXBRK_ZERO_CHAR_OFF	(1 << 8)
+#define MSM_BOOT_UART_DM_LOOPBACK		(1 << 7)
+
+#define PERIPH_BLK_BLSP			1
+
+/* UART Clock Selection Register */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_CSR(base)		((base) + 0xA0)
+#else
+#define MSM_BOOT_UART_DM_CSR(base)		((base) + 0x08)
+#endif
+
+/* UART DM TX FIFO Registers - 4 */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_TF(base, x)		((base) + 0x100+(4*(x)))
+#else
+#define MSM_BOOT_UART_DM_TF(base, x)		((base) + 0x70+(4*(x)))
+#endif
+
+/* UART Command Register */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_CR(base)		((base) + 0xA8)
+#else
+#define MSM_BOOT_UART_DM_CR(base)		((base) + 0x10)
+#endif
+#define MSM_BOOT_UART_DM_CR_RX_ENABLE		(1 << 0)
+#define MSM_BOOT_UART_DM_CR_RX_DISABLE		(1 << 1)
+#define MSM_BOOT_UART_DM_CR_TX_ENABLE		(1 << 2)
+#define MSM_BOOT_UART_DM_CR_TX_DISABLE		(1 << 3)
+
+/* UART Channel Command */
+#define MSM_BOOT_UART_DM_CR_CH_CMD_LSB(x)	((x & 0x0f) << 4)
+#define MSM_BOOT_UART_DM_CR_CH_CMD_MSB(x)	((x >> 4) << 11)
+#define MSM_BOOT_UART_DM_CR_CH_CMD(x)		\
+	(MSM_BOOT_UART_DM_CR_CH_CMD_LSB(x) | MSM_BOOT_UART_DM_CR_CH_CMD_MSB(x))
+#define MSM_BOOT_UART_DM_CMD_NULL		MSM_BOOT_UART_DM_CR_CH_CMD(0)
+#define MSM_BOOT_UART_DM_CMD_RESET_RX		MSM_BOOT_UART_DM_CR_CH_CMD(1)
+#define MSM_BOOT_UART_DM_CMD_RESET_TX		MSM_BOOT_UART_DM_CR_CH_CMD(2)
+#define MSM_BOOT_UART_DM_CMD_RESET_ERR_STAT	MSM_BOOT_UART_DM_CR_CH_CMD(3)
+#define MSM_BOOT_UART_DM_CMD_RES_BRK_CHG_INT	MSM_BOOT_UART_DM_CR_CH_CMD(4)
+#define MSM_BOOT_UART_DM_CMD_START_BRK		MSM_BOOT_UART_DM_CR_CH_CMD(5)
+#define MSM_BOOT_UART_DM_CMD_STOP_BRK		MSM_BOOT_UART_DM_CR_CH_CMD(6)
+#define MSM_BOOT_UART_DM_CMD_RES_CTS_N		MSM_BOOT_UART_DM_CR_CH_CMD(7)
+#define MSM_BOOT_UART_DM_CMD_RES_STALE_INT	MSM_BOOT_UART_DM_CR_CH_CMD(8)
+#define MSM_BOOT_UART_DM_CMD_PACKET_MODE	MSM_BOOT_UART_DM_CR_CH_CMD(9)
+#define MSM_BOOT_UART_DM_CMD_MODE_RESET		MSM_BOOT_UART_DM_CR_CH_CMD(C)
+#define MSM_BOOT_UART_DM_CMD_SET_RFR_N		MSM_BOOT_UART_DM_CR_CH_CMD(D)
+#define MSM_BOOT_UART_DM_CMD_RES_RFR_N		MSM_BOOT_UART_DM_CR_CH_CMD(E)
+#define MSM_BOOT_UART_DM_CMD_RES_TX_ERR		MSM_BOOT_UART_DM_CR_CH_CMD(10)
+#define MSM_BOOT_UART_DM_CMD_CLR_TX_DONE	MSM_BOOT_UART_DM_CR_CH_CMD(11)
+#define MSM_BOOT_UART_DM_CMD_RES_BRKSTRT_INT	MSM_BOOT_UART_DM_CR_CH_CMD(12)
+#define MSM_BOOT_UART_DM_CMD_RES_BRKEND_INT	MSM_BOOT_UART_DM_CR_CH_CMD(13)
+#define MSM_BOOT_UART_DM_CMD_RES_PER_FRM_INT	MSM_BOOT_UART_DM_CR_CH_CMD(14)
+
+/*UART General Command */
+#define MSM_UART_DM_CR_GENERAL_CMD(x)		((x) << 8)
+
+#define MSM_BOOT_UART_DM_GCMD_NULL		MSM_UART_DM_CR_GENERAL_CMD(0)
+#define MSM_BOOT_UART_DM_GCMD_CR_PROT_EN	MSM_UART_DM_CR_GENERAL_CMD(1)
+#define MSM_BOOT_UART_DM_GCMD_CR_PROT_DIS	MSM_UART_DM_CR_GENERAL_CMD(2)
+#define MSM_BOOT_UART_DM_GCMD_RES_TX_RDY_INT	MSM_UART_DM_CR_GENERAL_CMD(3)
+#define MSM_BOOT_UART_DM_GCMD_SW_FORCE_STALE	MSM_UART_DM_CR_GENERAL_CMD(4)
+#define MSM_BOOT_UART_DM_GCMD_ENA_STALE_EVT	MSM_UART_DM_CR_GENERAL_CMD(5)
+#define MSM_BOOT_UART_DM_GCMD_DIS_STALE_EVT	MSM_UART_DM_CR_GENERAL_CMD(6)
+
+/* UART Interrupt Mask Register */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_IMR(base)		((base) + 0xB0)
+#else
+#define MSM_BOOT_UART_DM_IMR(base)		((base) + 0x14)
+#endif
+
+#define MSM_BOOT_UART_DM_TXLEV			(1 << 0)
+#define MSM_BOOT_UART_DM_RXHUNT			(1 << 1)
+#define MSM_BOOT_UART_DM_RXBRK_CHNG		(1 << 2)
+#define MSM_BOOT_UART_DM_RXSTALE		(1 << 3)
+#define MSM_BOOT_UART_DM_RXLEV			(1 << 4)
+#define MSM_BOOT_UART_DM_DELTA_CTS		(1 << 5)
+#define MSM_BOOT_UART_DM_CURRENT_CTS		(1 << 6)
+#define MSM_BOOT_UART_DM_TX_READY		(1 << 7)
+#define MSM_BOOT_UART_DM_TX_ERROR		(1 << 8)
+#define MSM_BOOT_UART_DM_TX_DONE		(1 << 9)
+#define MSM_BOOT_UART_DM_RXBREAK_START		(1 << 10)
+#define MSM_BOOT_UART_DM_RXBREAK_END		(1 << 11)
+#define MSM_BOOT_UART_DM_PAR_FRAME_ERR_IRQ	(1 << 12)
+
+#define MSM_BOOT_UART_DM_IMR_ENABLED	(MSM_BOOT_UART_DM_TX_READY |	\
+					 MSM_BOOT_UART_DM_TXLEV |	\
+					 MSM_BOOT_UART_DM_RXSTALE)
+
+/* UART Interrupt Programming Register */
+#define MSM_BOOT_UART_DM_IPR(base)		((base) + 0x18)
+#define MSM_BOOT_UART_DM_STALE_TIMEOUT_LSB	0x0f
+#define MSM_BOOT_UART_DM_STALE_TIMEOUT_MSB	0	/* Not used currently */
+
+/* UART Transmit/Receive FIFO Watermark Register */
+#define MSM_BOOT_UART_DM_TFWR(base)		((base) + 0x1C)
+/* Interrupt is generated when FIFO level is less than or equal to this value */
+#define MSM_BOOT_UART_DM_TFW_VALUE		0
+
+#define MSM_BOOT_UART_DM_RFWR(base)		((base) + 0x20)
+/*Interrupt generated when no of words in RX FIFO is greater than this value */
+#define MSM_BOOT_UART_DM_RFW_VALUE		0
+
+/* UART Hunt Character Register */
+#define MSM_BOOT_UART_DM_HCR(base)		((base) + 0x24)
+
+/* Used for RX transfer initialization */
+#define MSM_BOOT_UART_DM_DMRX(base)		((base) + 0x34)
+
+/* Default DMRX value - any value bigger than FIFO size would be fine */
+#define MSM_BOOT_UART_DM_DMRX_DEF_VALUE		0x220
+
+/* Register to enable IRDA function */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_IRDA(base)		((base) + 0xB8)
+#else
+#define MSM_BOOT_UART_DM_IRDA(base)		((base) + 0x38)
+#endif
+
+/* UART Data Mover Enable Register */
+#define MSM_BOOT_UART_DM_DMEN(base)		((base) + 0x3C)
+
+/* Number of characters for Transmission */
+#define MSM_BOOT_UART_DM_NO_CHARS_FOR_TX(base) ((base) + 0x040)
+
+/* UART RX FIFO Base Address */
+#define MSM_BOOT_UART_DM_BADR(base)		((base) + 0x44)
+
+/* UART Status Register */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_SR(base)		((base) + 0x0A4)
+#else
+#define MSM_BOOT_UART_DM_SR(base)		((base) + 0x008)
+#endif
+#define MSM_BOOT_UART_DM_SR_RXRDY		(1 << 0)
+#define MSM_BOOT_UART_DM_SR_RXFULL		(1 << 1)
+#define MSM_BOOT_UART_DM_SR_TXRDY		(1 << 2)
+#define MSM_BOOT_UART_DM_SR_TXEMT		(1 << 3)
+#define MSM_BOOT_UART_DM_SR_UART_OVERRUN	(1 << 4)
+#define MSM_BOOT_UART_DM_SR_PAR_FRAME_ERR	(1 << 5)
+#define MSM_BOOT_UART_DM_RX_BREAK		(1 << 6)
+#define MSM_BOOT_UART_DM_HUNT_CHAR		(1 << 7)
+#define MSM_BOOT_UART_DM_RX_BRK_START_LAST	(1 << 8)
+
+/* UART Receive FIFO Registers - 4 in numbers */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_RF(base, x)		((base) + 0x140 + (4*(x)))
+#else
+#define MSM_BOOT_UART_DM_RF(base, x)		((base) + 0x70 + (4*(x)))
+#endif
+
+/* UART Masked Interrupt Status Register */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_MISR(base)		((base) + 0xAC)
+#else
+#define MSM_BOOT_UART_DM_MISR(base)		((base) + 0x10)
+#endif
+
+/* UART Interrupt Status Register */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_ISR(base)		((base) + 0xB4)
+#else
+#define MSM_BOOT_UART_DM_ISR(base)		((base) + 0x14)
+#endif
+
+/* Number of characters received since the end of last RX transfer */
+#if PERIPH_BLK_BLSP
+#define MSM_BOOT_UART_DM_RX_TOTAL_SNAP(base)  ((base) + 0xBC)
+#else
+#define MSM_BOOT_UART_DM_RX_TOTAL_SNAP(base)  ((base) + 0x38)
+#endif
+
+/* UART TX FIFO Status Register */
+#define MSM_BOOT_UART_DM_TXFS(base)		((base) + 0x4C)
+#define MSM_BOOT_UART_DM_TXFS_STATE_LSB(x)	\
+		MSM_BOOT_UART_DM_EXTR_BITS(x, 0, 6)
+#define MSM_BOOT_UART_DM_TXFS_STATE_MSB(x)	\
+		MSM_BOOT_UART_DM_EXTR_BITS(x, 14, 31)
+#define MSM_BOOT_UART_DM_TXFS_BUF_STATE(x)	\
+		MSM_BOOT_UART_DM_EXTR_BITS(x, 7, 9)
+#define MSM_BOOT_UART_DM_TXFS_ASYNC_STATE(x)	\
+		MSM_BOOT_UART_DM_EXTR_BITS(x, 10, 13)
+
+/* UART RX FIFO Status Register */
+#define MSM_BOOT_UART_DM_RXFS(base)		((base) + 0x50)
+#define MSM_BOOT_UART_DM_RXFS_STATE_LSB(x)	\
+		MSM_BOOT_UART_DM_EXTR_BITS(x, 0, 6)
+#define MSM_BOOT_UART_DM_RXFS_STATE_MSB(x)	\
+		MSM_BOOT_UART_DM_EXTR_BITS(x, 14, 31)
+#define MSM_BOOT_UART_DM_RXFS_BUF_STATE(x)	\
+		MSM_BOOT_UART_DM_EXTR_BITS(x, 7, 9)
+#define MSM_BOOT_UART_DM_RXFS_ASYNC_STATE(x)	\
+		MSM_BOOT_UART_DM_EXTR_BITS(x, 10, 13)
+
+/* Macros for Common Errors */
+#define MSM_BOOT_UART_DM_E_FAILURE		1
+#define MSM_BOOT_UART_DM_E_TIMEOUT		2
+#define MSM_BOOT_UART_DM_E_INVAL		3
+#define MSM_BOOT_UART_DM_E_MALLOC_FAIL		4
+#define MSM_BOOT_UART_DM_E_RX_NOT_READY		5
+
+#define UART1_DM_BASE				((void *)0x078af000)
+#define UART2_DM_BASE				((void *)0x078b1000)
+
+enum {
+	BLSP1_UART1,
+	BLSP1_UART2,
+};
+
+#define FIFO_DATA_SIZE	4
+
+struct uart_params_t {
+	void *uart_dm_base;
+	unsigned int blsp_uart;
+};
+
+static struct console_input_driver consin = {
+	.havekey = serial_havechar,
+	.getchar = serial_getchar,
+};
+
+static struct console_output_driver consout = {
+	.putchar = serial_putchar,
+};
+
+static struct uart_params_t uart_board_param = {};
+
+/**
+ * msm_boot_uart_dm_init_rx_transfer - Init Rx transfer
+ * @uart_dm_base: UART controller base address
+ */
+static unsigned int msm_boot_uart_dm_init_rx_transfer(void *uart_dm_base)
+{
+	/* Reset receiver */
+	write32(MSM_BOOT_UART_DM_CR(uart_dm_base),
+		MSM_BOOT_UART_DM_CMD_RESET_RX);
+
+	/* Enable receiver */
+	write32(MSM_BOOT_UART_DM_CR(uart_dm_base),
+		MSM_BOOT_UART_DM_CR_RX_ENABLE);
+	write32(MSM_BOOT_UART_DM_DMRX(uart_dm_base),
+		MSM_BOOT_UART_DM_DMRX_DEF_VALUE);
+
+	/* Clear stale event */
+	write32(MSM_BOOT_UART_DM_CR(uart_dm_base),
+		MSM_BOOT_UART_DM_CMD_RES_STALE_INT);
+
+	/* Enable stale event */
+	write32(MSM_BOOT_UART_DM_CR(uart_dm_base),
+		MSM_BOOT_UART_DM_GCMD_ENA_STALE_EVT);
+
+	return 0;
+}
+
+static unsigned int msm_boot_uart_dm_init(void  *uart_dm_base);
+
+static int valid_data = 0;
+
+static unsigned int word = 0;
+
+/**
+ * msm_boot_uart_dm_read - reads a word from the RX FIFO.
+ * @data: location where the read data is stored
+ * @count: no of valid data in the FIFO
+ *
+ * Reads a word from the RX FIFO. If no data is available
+ * returns %MSM_BOOT_UART_DM_E_RX_NOT_READY.
+ */
+static unsigned int
+msm_boot_uart_dm_read(unsigned int *data, int *count)
+{
+	static int total_rx_data = 0;
+	static int rx_data_read = 0;
+	void *base;
+	uint32_t status_reg;
+
+	base = uart_board_param.uart_dm_base;
+
+	if (data == NULL)
+		return MSM_BOOT_UART_DM_E_INVAL;
+
+	status_reg = read32(MSM_BOOT_UART_DM_MISR(base));
+
+	/* Check for DM_RXSTALE for RX transfer to finish */
+	while (!(status_reg & MSM_BOOT_UART_DM_RXSTALE)) {
+		status_reg = read32(MSM_BOOT_UART_DM_MISR(base));
+		return MSM_BOOT_UART_DM_E_RX_NOT_READY;
+	}
+
+	/* Check for Overrun error. We'll just reset Error Status */
+	if (read32(MSM_BOOT_UART_DM_SR(base)) &
+			MSM_BOOT_UART_DM_SR_UART_OVERRUN) {
+		write32(MSM_BOOT_UART_DM_CR(base),
+			MSM_BOOT_UART_DM_CMD_RESET_ERR_STAT);
+		total_rx_data = rx_data_read = 0;
+		msm_boot_uart_dm_init(base);
+		return MSM_BOOT_UART_DM_E_RX_NOT_READY;
+	}
+
+	/* Read UART_DM_RX_TOTAL_SNAP for actual number of bytes received */
+	if (total_rx_data == 0)
+		total_rx_data =  read32(MSM_BOOT_UART_DM_RX_TOTAL_SNAP(base));
+
+	/* Data available in FIFO; read a word. */
+	*data = read32(MSM_BOOT_UART_DM_RF(base, 0));
+
+	/* increment the total count of chars we've read so far */
+	rx_data_read += FIFO_DATA_SIZE;
+
+	/* actual count of valid data in word */
+	*count = ((total_rx_data < rx_data_read) ?
+			(FIFO_DATA_SIZE - (rx_data_read - total_rx_data)) :
+			FIFO_DATA_SIZE);
+
+	/* If there are still data left in FIFO we'll read them before
+	 * initializing RX Transfer again
+	 */
+	if (rx_data_read < total_rx_data)
+		return 0;
+
+	msm_boot_uart_dm_init_rx_transfer(base);
+	total_rx_data = rx_data_read = 0;
+
+	return 0;
+}
+
+void serial_putchar(unsigned int data)
+{
+	int num_of_chars = 1;
+	void *base = uart_board_param.uart_dm_base;
+
+	if (data == '\n') {
+		num_of_chars++;
+		data = (data << 8) | '\r';
+	}
+
+	/* Wait until transmit FIFO is empty. */
+	while (!(read32(MSM_BOOT_UART_DM_SR(base)) &
+		 MSM_BOOT_UART_DM_SR_TXEMT))
+		udelay(1);
+	/*
+	 * TX FIFO is ready to accept new character(s). First write number of
+	 * characters to be transmitted.
+	 */
+	write32(MSM_BOOT_UART_DM_NO_CHARS_FOR_TX(base), num_of_chars);
+
+	/* And now write the character(s) */
+	write32(MSM_BOOT_UART_DM_TF(base, 0), data);
+}
+
+/*
+ * msm_boot_uart_dm_reset - resets UART controller
+ * @base: UART controller base address
+ */
+static unsigned int msm_boot_uart_dm_reset(void *base)
+{
+	write32(MSM_BOOT_UART_DM_CR(base), MSM_BOOT_UART_DM_CMD_RESET_RX);
+	write32(MSM_BOOT_UART_DM_CR(base), MSM_BOOT_UART_DM_CMD_RESET_TX);
+	write32(MSM_BOOT_UART_DM_CR(base),
+		MSM_BOOT_UART_DM_CMD_RESET_ERR_STAT);
+	write32(MSM_BOOT_UART_DM_CR(base), MSM_BOOT_UART_DM_CMD_RES_TX_ERR);
+	write32(MSM_BOOT_UART_DM_CR(base), MSM_BOOT_UART_DM_CMD_RES_STALE_INT);
+
+	return 0;
+}
+
+/*
+ * msm_boot_uart_dm_init - initilaizes UART controller
+ * @uart_dm_base: UART controller base address
+ */
+unsigned int msm_boot_uart_dm_init(void  *uart_dm_base)
+{
+	/* Configure UART mode registers MR1 and MR2 */
+	/* Hardware flow control isn't supported */
+	write32(MSM_BOOT_UART_DM_MR1(uart_dm_base), 0x0);
+
+	/* 8-N-1 configuration: 8 data bits - No parity - 1 stop bit */
+	write32(MSM_BOOT_UART_DM_MR2(uart_dm_base),
+		MSM_BOOT_UART_DM_8_N_1_MODE);
+
+	/* Configure Interrupt Mask register IMR */
+	write32(MSM_BOOT_UART_DM_IMR(uart_dm_base),
+		MSM_BOOT_UART_DM_IMR_ENABLED);
+
+	/*
+	 * Configure Tx and Rx watermarks configuration registers
+	 * TX watermark value is set to 0 - interrupt is generated when
+	 * FIFO level is less than or equal to 0
+	 */
+	write32(MSM_BOOT_UART_DM_TFWR(uart_dm_base),
+		MSM_BOOT_UART_DM_TFW_VALUE);
+
+	/* RX watermark value */
+	write32(MSM_BOOT_UART_DM_RFWR(uart_dm_base),
+		MSM_BOOT_UART_DM_RFW_VALUE);
+
+	/* Configure Interrupt Programming Register */
+	/* Set initial Stale timeout value */
+	write32(MSM_BOOT_UART_DM_IPR(uart_dm_base),
+		MSM_BOOT_UART_DM_STALE_TIMEOUT_LSB);
+
+	/* Configure IRDA if required */
+	/* Disabling IRDA mode */
+	write32(MSM_BOOT_UART_DM_IRDA(uart_dm_base), 0x0);
+
+	/* Configure hunt character value in HCR register */
+	/* Keep it in reset state */
+	write32(MSM_BOOT_UART_DM_HCR(uart_dm_base), 0x0);
+
+	/*
+	 * Configure Rx FIFO base address
+	 * Both TX/RX shares same SRAM and default is half-n-half.
+	 * Sticking with default value now.
+	 * As such RAM size is (2^RAM_ADDR_WIDTH, 32-bit entries).
+	 * We have found RAM_ADDR_WIDTH = 0x7f
+	 */
+
+	/* Issue soft reset command */
+	msm_boot_uart_dm_reset(uart_dm_base);
+
+	/* Enable/Disable Rx/Tx DM interfaces */
+	/* Data Mover not currently utilized. */
+	write32(MSM_BOOT_UART_DM_DMEN(uart_dm_base), 0x0);
+
+	/* Enable transmitter */
+	write32(MSM_BOOT_UART_DM_CR(uart_dm_base),
+		MSM_BOOT_UART_DM_CR_TX_ENABLE);
+
+	/* Initialize Receive Path */
+	msm_boot_uart_dm_init_rx_transfer(uart_dm_base);
+
+	return 0;
+}
+
+/**
+ * serial_havechar - checks if data available for reading
+ *
+ * Returns 1 if data available, 0 otherwise
+ */
+int serial_havechar(void)
+{
+	/* Return if data is already read */
+	if (valid_data)
+		return 1;
+
+	/* Read data from the FIFO */
+	if (msm_boot_uart_dm_read(&word, &valid_data) != 0)
+		return 0;
+
+	return 1;
+}
+
+/**
+ * qcs405_serial_getc - reads a character
+ *
+ * Returns the character read from serial port.
+ */
+int serial_getchar(void)
+{
+	uint8_t byte;
+
+	while (!serial_havechar())
+		;	/* wait for incoming data */
+
+	byte = (uint8_t)(word & 0xff);
+	word = word >> 8;
+	valid_data--;
+
+	return byte;
+}
+
+/* For simplicity sake let's rely on coreboot initalizing the UART. */
+void serial_console_init(void)
+{
+	struct cb_serial *sc_ptr = lib_sysinfo.serial;
+
+	if (!sc_ptr)
+		return;
+
+	uart_board_param.uart_dm_base = (void *)(uintptr_t)sc_ptr->baseaddr;
+
+	/* TODO: We should rely on coreboot init. */
+	msm_boot_uart_dm_init(uart_board_param.uart_dm_base);
+
+	console_add_output_driver(&consout);
+	console_add_input_driver(&consin);
+}