Driver for 16550 UART interface

This patch adds driver for the 16550 UART interface. The driver is exposed
as a console, which platforms can use to dump their boot/crash logs.
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

Makefile

@@ -212,6 +212,7 @@ INCLUDES		+=	-Iinclude/bl31			\
 				-Iinclude/drivers		\
 				-Iinclude/drivers/arm		\
 				-Iinclude/drivers/io		\
+				-Iinclude/drivers/ti/uart	\
 				-Iinclude/lib			\
 				-Iinclude/lib/aarch64		\
 				-Iinclude/lib/cpus/aarch64	\

drivers/ti/uart/16550_console.S

+/*
+ * Copyright (c) 2015, ARM Limited and Contributors. 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 ARM 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 BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER 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 <arch.h>
+#include <asm_macros.S>
+#include <uart_16550.h>
+
+	.globl	console_core_init
+	.globl	console_core_putc
+	.globl	console_core_getc
+
+	/* -----------------------------------------------
+	 * int console_core_init(unsigned long base_addr,
+	 * unsigned int uart_clk, unsigned int baud_rate)
+	 * Function to initialize the console without a
+	 * C Runtime to print debug information. This
+	 * function will be accessed by console_init and
+	 * crash reporting.
+	 * In: x0 - console base address
+	 *     w1 - Uart clock in Hz
+	 *     w2 - Baud rate
+	 * Out: return 1 on success
+	 * Clobber list : x1, x2, x3
+	 * -----------------------------------------------
+	 */
+func console_core_init
+	/* Check the input base address */
+	cbz	x0, init_fail
+	/* Check baud rate and uart clock for sanity */
+	cbz	w1, init_fail
+	cbz	w2, init_fail
+
+	/* Program the baudrate */
+	/* Divisor =  Uart clock / (16 * baudrate) */
+	lsl	w2, w2, #4
+	udiv	w2, w1, w2
+	and	w1, w2, #0xff		/* w1 = DLL */
+	lsr	w2, w2, #8
+	and	w2, w2, #0xff		/* w2 = DLLM */
+	ldr	w3, [x0, #UARTLCR]
+	orr	w3, w3, #UARTLCR_DLAB
+	str	w3, [x0, #UARTLCR]	/* enable DLL, DLLM programming */
+	str	w1, [x0, #UARTDLL]	/* program DLL */
+	str	w2, [x0, #UARTDLLM]	/* program DLLM */
+	mov	w2, #~UARTLCR_DLAB
+	and	w3, w3, w2
+	str	w3, [x0, #UARTLCR]	/* disable DLL, DLLM programming */
+
+	/* 8n1 */
+	mov	w3, #3
+	str	w3, [x0, #UARTLCR]
+	/* no interrupt */
+	mov	w3, #0
+	str	w3, [x0, #UARTIER]
+	/* enable fifo, DMA */
+	mov	w3, #(UARTFCR_FIFOEN | UARTFCR_DMAEN)
+	str	w3, [x0, #UARTFCR]
+	/* DTR + RTS */
+	mov	w3, #3
+	str	w3, [x0, #UARTMCR]
+	mov	w0, #1
+init_fail:
+	ret
+endfunc console_core_init
+
+	/* --------------------------------------------------------
+	 * int console_core_putc(int c, unsigned int base_addr)
+	 * Function to output a character over the console. It
+	 * returns the character printed on success or -1 on error.
+	 * In : w0 - character to be printed
+	 *      x1 - console base address
+	 * Out : return -1 on error else return character.
+	 * Clobber list : x2
+	 * --------------------------------------------------------
+	 */
+func console_core_putc
+	/* Check the input parameter */
+	cbz	x1, putc_error
+
+	/* Prepend '\r' to '\n' */
+	cmp	w0, #0xA
+	b.ne	2f
+	/* Check if the transmit FIFO is full */
+1:	ldr	w2, [x1, #UARTLSR]
+	and	w2, w2, #(UARTLSR_TEMT | UARTLSR_THRE)
+	cmp	w2, #(UARTLSR_TEMT | UARTLSR_THRE)
+	b.ne	1b
+	mov	w2, #0xD		/* '\r' */
+	str	w2, [x1, #UARTTX]
+	ldr	w2, [x1, #UARTFCR]
+	orr	w2, w2, #UARTFCR_TXCLR
+	str	w2, [x1, #UARTFCR]
+
+	/* Check if the transmit FIFO is full */
+2:	ldr	w2, [x1, #UARTLSR]
+	and	w2, w2, #(UARTLSR_TEMT | UARTLSR_THRE)
+	cmp	w2, #(UARTLSR_TEMT | UARTLSR_THRE)
+	b.ne	2b
+	str	w0, [x1, #UARTTX]
+	ldr	w2, [x1, #UARTFCR]
+	orr	w2, w2, #UARTFCR_TXCLR
+	str	w2, [x1, #UARTFCR]
+	ret
+putc_error:
+	mov	w0, #-1
+	ret
+endfunc console_core_putc
+
+	/* ---------------------------------------------
+	 * int console_core_getc(void)
+	 * Function to get a character from the console.
+	 * It returns the character grabbed on success
+	 * or -1 on error.
+	 * In : w0 - console base address
+	 * Out : return -1 on error else return character.
+	 * Clobber list : x0, x1
+	 * ---------------------------------------------
+	 */
+func console_core_getc
+	/* Check if the receive FIFO is empty */
+1:	ldr	w1, [x0, #UARTLSR]
+	tbz	w1, #UARTLSR_RDR, 1b
+	ldr	w0, [x0, #UARTRX]
+	ret
+getc_error:
+	mov	w0, #-1
+	ret
+endfunc console_core_getc

include/drivers/ti/uart/uart_16550.h

+/*
+ * Copyright (c) 2015, ARM Limited and Contributors. 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 ARM 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 BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER 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.
+ */
+
+#ifndef __UART_16550_H__
+#define __UART_16550_H__
+
+/* UART16550 Registers */
+#define UARTTX			0x0
+#define UARTRX			0x0
+#define UARTDLL			0x0
+#define UARTIER			0x4
+#define UARTDLLM		0x4
+#define UARTIIR			0x8
+#define UARTFCR			0x8
+#define UARTLCR			0xc
+#define UARTMCR			0x10
+#define UARTLSR			0x14
+#define UARTMSR			0x18
+#define UARTSPR			0x1c
+#define UARTCSR			0x20
+#define UARTRXFIFOCFG		0x24
+#define UARTMIE			0x28
+#define UARTVNDR		0x2c
+#define UARTASR			0x3c
+
+/* FIFO Control Register bits */
+#define UARTFCR_FIFOMD_16450	(0 << 6)
+#define UARTFCR_FIFOMD_16550	(1 << 6)
+#define UARTFCR_RXTRIG_1	(0 << 6)
+#define UARTFCR_RXTRIG_4	(1 << 6)
+#define UARTFCR_RXTRIG_8	(2 << 6)
+#define UARTFCR_RXTRIG_16	(3 << 6)
+#define UARTFCR_TXTRIG_1	(0 << 4)
+#define UARTFCR_TXTRIG_4	(1 << 4)
+#define UARTFCR_TXTRIG_8	(2 << 4)
+#define UARTFCR_TXTRIG_16	(3 << 4)
+#define UARTFCR_DMAEN		(1 << 3)	/* Enable DMA mode */
+#define UARTFCR_TXCLR		(1 << 2)	/* Clear contents of Tx FIFO */
+#define UARTFCR_RXCLR		(1 << 1)	/* Clear contents of Rx FIFO */
+#define UARTFCR_FIFOEN		(1 << 0)	/* Enable the Tx/Rx FIFO */
+
+/* Line Control Register bits */
+#define UARTLCR_DLAB		(1 << 7)	/* Divisor Latch Access */
+#define UARTLCR_SETB		(1 << 6)	/* Set BREAK Condition */
+#define UARTLCR_SETP		(1 << 5)	/* Set Parity to LCR[4] */
+#define UARTLCR_EVEN		(1 << 4)	/* Even Parity Format */
+#define UARTLCR_PAR		(1 << 3)	/* Parity */
+#define UARTLCR_STOP		(1 << 2)	/* Stop Bit */
+#define UARTLCR_WORDSZ_5	0		/* Word Length of 5 */
+#define UARTLCR_WORDSZ_6	1		/* Word Length of 6 */
+#define UARTLCR_WORDSZ_7	2		/* Word Length of 7 */
+#define UARTLCR_WORDSZ_8	3		/* Word Length of 8 */
+
+/* Line Status Register bits */
+#define UARTLSR_RXFIFOEMT	(1 << 9)	/* Rx Fifo Empty */
+#define UARTLSR_TXFIFOFULL	(1 << 8)	/* Tx Fifo Full */
+#define UARTLSR_RXFIFOERR	(1 << 7)	/* Rx Fifo Error */
+#define UARTLSR_TEMT		(1 << 6)	/* Tx Shift Register Empty */
+#define UARTLSR_THRE		(1 << 5)	/* Tx Holding Register Empty */
+#define UARTLSR_BRK		(1 << 4)	/* Break Condition Detected */
+#define UARTLSR_FERR		(1 << 3)	/* Framing Error */
+#define UARTLSR_PERR		(1 << 3)	/* Parity Error */
+#define UARTLSR_OVRF		(1 << 2)	/* Rx Overrun Error */
+#define UARTLSR_RDR		(1 << 2)	/* Rx Data Ready */
+
+#endif	/* __UART_16550_H__ */