serial: Combine Tegra and Rockchip UARTs to generic 8250_mmio32

We have two drivers for a 100%-identical peripheral right now, mostly
because we couldn't come up with a good common name for it back when we
checked it in. That seems like a pretty silly reason in the long run.

Both Tegra and Rockchip SoCs contain UARTs that use the common 8250
register interface (at least for the very basic byte-per-byte transmit
and receive parts we care about), memory-mapped with a 32-bit register
stride. This patch combines them to a single 8250_mmio32 driver (which
also fixes a problem when booting Rockchip without serial enabled, since
that driver forgot to check for serial initialization when registering
its console drivers). The register accesses are done using readl/writel
(as Rockchip did before), since the registers are documented as 32-bit
length (with top 24 bits RAZ/WI), although the Tegra SoC doesn't enforce
APB accesses to have the full word length. Also fixed checkpatch stuff.

A day may come when we can also merge this driver into the (completely
different, with more complicated features and #ifdefs) 8250 driver for
x86 (which has MMIO support for 8-bit register stride only), both here
and in coreboot. But it is not this day. This day I just want to get rid
of a 99% identical file without expending too much effort.

BUG=None
TEST=Booted on Veyron_Pinky and Nyan_Blaze with and without serial
enabled, both worked fine (although Veyron has another kernel issue).

Change-Id: I85c004a75cc5aa7cb40098002d3e00a62c1c5f2d
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: e7959c19356d2922aa414866016540ad9ee2ffa8
Original-Change-Id: Ib84d00f52ff2c48398c75f77f6a245e658ffdeb9
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/225102
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9387
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

3 files changed, 25 insertions, 141 deletions

diff --git a/payloads/libpayload/drivers/Makefile.inc b/payloads/libpayload/drivers/Makefile.inc
index 6dc1403f2f..f3b147de36 100644
--- a/payloads/libpayload/drivers/Makefile.inc
+++ b/payloads/libpayload/drivers/Makefile.inc
@@ -35,9 +35,8 @@ libc-$(CONFIG_LP_SPEAKER) += speaker.c
 
 libc-$(CONFIG_LP_8250_SERIAL_CONSOLE) += serial/8250.c
 libc-$(CONFIG_LP_S5P_SERIAL_CONSOLE) += serial/s5p.c
-libc-$(CONFIG_LP_TEGRA_SERIAL_CONSOLE) += serial/tegra.c
+libc-$(CONFIG_LP_8250_MMIO32_SERIAL_CONSOLE) += serial/8250_mmio32.c
 libc-$(CONFIG_LP_IPQ806X_SERIAL_CONSOLE) += serial/ipq806x.c
-libc-$(CONFIG_LP_RK_SERIAL_CONSOLE) += serial/rk_serial.c
 libc-$(CONFIG_LP_BG4CD_SERIAL_CONSOLE) += serial/bg4cd.c
 libc-$(CONFIG_LP_PC_KEYBOARD) += keyboard.c
 
diff --git a/payloads/libpayload/drivers/serial/tegra.c b/payloads/libpayload/drivers/serial/8250_mmio32.c
index a3dad2b09f..285f7f6dac 100644
--- a/payloads/libpayload/drivers/serial/tegra.c
+++ b/payloads/libpayload/drivers/serial/8250_mmio32.c
@@ -28,7 +28,7 @@
 #include <libpayload.h>
 #include <stdint.h>
 
-struct tegra_uart {
+struct mmio32_uart {
 	union {
 		uint32_t thr; // Transmit holding register.
 		uint32_t rbr; // Receive buffer register.
@@ -49,47 +49,47 @@ struct tegra_uart {
 } __attribute__ ((packed));
 
 enum {
-	TEGRA_UART_LSR_DR = 0x1 << 0, // Data ready.
-	TEGRA_UART_LSR_OE = 0x1 << 1, // Overrun.
-	TEGRA_UART_LSR_PE = 0x1 << 2, // Parity error.
-	TEGRA_UART_LSR_FE = 0x1 << 3, // Framing error.
-	TEGRA_UART_LSR_BI = 0x1 << 4, // Break.
-	TEGRA_UART_LSR_THRE = 0x1 << 5, // Xmit holding register empty.
-	TEGRA_UART_LSR_TEMT = 0x1 << 6, // Xmitter empty.
-	TEGRA_UART_LSR_ERR = 0x1 << 7 // Error.
+	LSR_DR = 0x1 << 0, // Data ready.
+	LSR_OE = 0x1 << 1, // Overrun.
+	LSR_PE = 0x1 << 2, // Parity error.
+	LSR_FE = 0x1 << 3, // Framing error.
+	LSR_BI = 0x1 << 4, // Break.
+	LSR_THRE = 0x1 << 5, // Xmit holding register empty.
+	LSR_TEMT = 0x1 << 6, // Xmitter empty.
+	LSR_ERR = 0x1 << 7 // Error.
 };
 
-static struct tegra_uart *uart_regs;
+static struct mmio32_uart *uart = NULL;
 
 void serial_putchar(unsigned int c)
 {
-	while (!(readb(&uart_regs->lsr) & TEGRA_UART_LSR_THRE));
-	writeb(c, &uart_regs->thr);
+	while (!(readl(&uart->lsr) & LSR_THRE))
+		/* wait for transmit register to clear */;
+
+	writel((char)c, &uart->thr);
 	if (c == '\n')
 		serial_putchar('\r');
 }
 
 int serial_havechar(void)
 {
-	uint8_t lsr = readb(&uart_regs->lsr);
-	return (lsr & TEGRA_UART_LSR_DR) == TEGRA_UART_LSR_DR;
+	uint8_t lsr = readl(&uart->lsr);
+	return (lsr & LSR_DR) == LSR_DR;
 }
 
 int serial_getchar(void)
 {
 	while (!serial_havechar())
-	{;}
+		/* wait for character */;
 
-	return readb(&uart_regs->rbr);
+	return readl(&uart->rbr);
 }
 
-static struct console_output_driver tegra_serial_output =
-{
+static struct console_output_driver mmio32_serial_output = {
 	.putchar = &serial_putchar
 };
 
-static struct console_input_driver tegra_serial_input =
-{
+static struct console_input_driver mmio32_serial_input = {
 	.havekey = &serial_havechar,
 	.getchar = &serial_getchar
 };
@@ -99,15 +99,15 @@ void serial_init(void)
 	if (!lib_sysinfo.serial || !lib_sysinfo.serial->baseaddr)
 		return;
 
-	uart_regs = (struct tegra_uart *)(uintptr_t)lib_sysinfo.serial->baseaddr;
+	uart = (struct mmio32_uart *)(uintptr_t)lib_sysinfo.serial->baseaddr;
 }
 
 void serial_console_init(void)
 {
 	serial_init();
 
-	if (uart_regs) {
-		console_add_output_driver(&tegra_serial_output);
-		console_add_input_driver(&tegra_serial_input);
+	if (uart) {
+		console_add_output_driver(&mmio32_serial_output);
+		console_add_input_driver(&mmio32_serial_input);
 	}
 }
diff --git a/payloads/libpayload/drivers/serial/rk_serial.c b/payloads/libpayload/drivers/serial/rk_serial.c
deleted file mode 100644
index 91a6e1bde9..0000000000
--- a/payloads/libpayload/drivers/serial/rk_serial.c
+++ /dev/null
@@ -1,115 +0,0 @@
-/*
- * This file is part of the coreboot project.
- *
- * Copyright (C) 2014 Rockchip Electronics
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
- */
-#include <libpayload-config.h>
-#include <libpayload.h>
-struct rk_uart {
-	union {
-		u32 uart_thr;	/* Transmit holding register. */
-		u32 uart_rbr;	/* Receive buffer register. */
-		u32 uart_dll;	/* Divisor latch lsb. */
-	};
-	union {
-		u32 uart_ier;	/* Interrupt enable register. */
-		u32 uart_dlh;	/* Divisor latch msb. */
-	};
-	union {
-		uint32_t uart_iir;	/* Interrupt identification register. */
-		uint32_t uart_fcr;	/* FIFO control register. */
-	};
-	u32 uart_lcr;
-	u32 uart_mcr;
-	u32 uart_lsr;
-	u32 uart_msr;
-	u32 uart_scr;
-	u32 reserved1[(0x30 - 0x20) / 4];
-	u32 uart_srbr[(0x70 - 0x30) / 4];
-	u32 uart_far;
-	u32 uart_tfr;
-	u32 uart_rfw;
-	u32 uart_usr;
-	u32 uart_tfl;
-	u32 uart_rfl;
-	u32 uart_srr;
-	u32 uart_srts;
-	u32 uart_sbcr;
-	u32 uart_sdmam;
-	u32 uart_sfe;
-	u32 uart_srt;
-	u32 uart_stet;
-	u32 uart_htx;
-	u32 uart_dmasa;
-	u32 reserver2[(0xf4 - 0xac) / 4];
-	u32 uart_cpr;
-	u32 uart_ucv;
-	u32 uart_ctr;
-};
-enum {
-	UART_LSR_DR = 0x1 << 0,	/* Data ready. */
-	UART_LSR_OE = 0x1 << 1,	/* Overrun. */
-	UART_LSR_PE = 0x1 << 2,	/* Parity error. */
-	UART_LSR_FE = 0x1 << 3,	/* Framing error. */
-	UART_LSR_BI = 0x1 << 4,	/* Break. */
-	UART_LSR_THRE = 0x1 << 5,	/* Xmit holding register empty. */
-	UART_LSR_TEMT = 0x1 << 6,	/* Xmitter empty. */
-	UART_LSR_ERR = 0x1 << 7	/* Error. */
-};
-
-static struct rk_uart *uart_regs;
-void serial_putchar(unsigned int c)
-{
-	while (!(readl(&uart_regs->uart_lsr) & UART_LSR_THRE));
-	writel((c & 0xff), &uart_regs->uart_thr);
-	if (c == '\n')
-		serial_putchar('\r');
-}
-
-int serial_havechar(void)
-{
-	uint8_t lsr = readl(&uart_regs->uart_lsr);
-	return (lsr & UART_LSR_DR) == UART_LSR_DR;
-}
-
-int serial_getchar(void)
-{
-	while (!serial_havechar());
-	return readl(&uart_regs->uart_rbr)&0xff;
-}
-
-static struct console_input_driver consin = {
-	.havekey = &serial_havechar,
-	.getchar = &serial_getchar
-};
-
-static struct console_output_driver consout = {.putchar = &serial_putchar
-};
-
-void serial_init(void)
-{
-	if (!lib_sysinfo.serial || !lib_sysinfo.serial->baseaddr)
-		return;
-
-	uart_regs = (struct rk_uart *)lib_sysinfo.serial->baseaddr;
-}
-
-void serial_console_init(void)
-{
-	serial_init();
-	console_add_input_driver(&consin);
-	console_add_output_driver(&consout);
-}