MIPS: Add support for PIC32MZDA platform

This adds support for the Microchip PIC32 MIPS microcontroller with the
specific variant PIC32MZDA. PIC32MZDA is based on the MIPS m14KEc core
and boots using device tree.

This includes an early pin setup and early clock setup needed prior to
device tree being initialized. In additon, an interface is provided to
synchronize access to registers shared across several peripherals.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12097/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 171 insertions, 0 deletions

diff --git a/arch/mips/pic32/pic32mzda/early_console.c b/arch/mips/pic32/pic32mzda/early_console.c
new file mode 100644
index 000000000000..d7b783463fac
--- /dev/null
+++ b/arch/mips/pic32/pic32mzda/early_console.c
@@ -0,0 +1,171 @@
+/*
+ * Joshua Henderson <joshua.henderson@microchip.com>
+ * Copyright (C) 2015 Microchip Technology Inc.  All rights reserved.
+ *
+ *  This program is free software; you can distribute it and/or modify it
+ *  under the terms of the GNU General Public License (Version 2) as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope 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.
+ */
+#include <asm/mach-pic32/pic32.h>
+#include <asm/fw/fw.h>
+
+#include "pic32mzda.h"
+#include "early_pin.h"
+
+/* Default early console parameters */
+#define EARLY_CONSOLE_PORT	1
+#define EARLY_CONSOLE_BAUDRATE	115200
+
+#define UART_ENABLE		BIT(15)
+#define UART_ENABLE_RX		BIT(12)
+#define UART_ENABLE_TX		BIT(10)
+#define UART_TX_FULL		BIT(9)
+
+/* UART1(x == 0) - UART6(x == 5) */
+#define UART_BASE(x)	((x) * 0x0200)
+#define U_MODE(x)	UART_BASE(x)
+#define U_STA(x)	(UART_BASE(x) + 0x10)
+#define U_TXR(x)	(UART_BASE(x) + 0x20)
+#define U_BRG(x)	(UART_BASE(x) + 0x40)
+
+static void __iomem *uart_base;
+static char console_port = -1;
+
+static int __init configure_uart_pins(int port)
+{
+	switch (port) {
+	case 1:
+		pic32_pps_input(IN_FUNC_U2RX, IN_RPB0);
+		pic32_pps_output(OUT_FUNC_U2TX, OUT_RPG9);
+		break;
+	case 5:
+		pic32_pps_input(IN_FUNC_U6RX, IN_RPD0);
+		pic32_pps_output(OUT_FUNC_U6TX, OUT_RPB8);
+		break;
+	default:
+		return -1;
+	}
+
+	return 0;
+}
+
+static void __init configure_uart(char port, int baud)
+{
+	u32 pbclk;
+
+	pbclk = pic32_get_pbclk(2);
+
+	__raw_writel(0, uart_base + U_MODE(port));
+	__raw_writel(((pbclk / baud) / 16) - 1, uart_base + U_BRG(port));
+	__raw_writel(UART_ENABLE, uart_base + U_MODE(port));
+	__raw_writel(UART_ENABLE_TX | UART_ENABLE_RX,
+		     uart_base + PIC32_SET(U_STA(port)));
+}
+
+static void __init setup_early_console(char port, int baud)
+{
+	if (configure_uart_pins(port))
+		return;
+
+	console_port = port;
+	configure_uart(console_port, baud);
+}
+
+static char * __init pic32_getcmdline(void)
+{
+	/*
+	 * arch_mem_init() has not been called yet, so we don't have a real
+	 * command line setup if using CONFIG_CMDLINE_BOOL.
+	 */
+#ifdef CONFIG_CMDLINE_OVERRIDE
+	return CONFIG_CMDLINE;
+#else
+	return fw_getcmdline();
+#endif
+}
+
+static int __init get_port_from_cmdline(char *arch_cmdline)
+{
+	char *s;
+	int port = -1;
+
+	if (!arch_cmdline || *arch_cmdline == '\0')
+		goto _out;
+
+	s = strstr(arch_cmdline, "earlyprintk=");
+	if (s) {
+		s = strstr(s, "ttyS");
+		if (s)
+			s += 4;
+		else
+			goto _out;
+
+		port = (*s) - '0';
+	}
+
+_out:
+	return port;
+}
+
+static int __init get_baud_from_cmdline(char *arch_cmdline)
+{
+	char *s;
+	int baud = -1;
+
+	if (!arch_cmdline || *arch_cmdline == '\0')
+		goto _out;
+
+	s = strstr(arch_cmdline, "earlyprintk=");
+	if (s) {
+		s = strstr(s, "ttyS");
+		if (s)
+			s += 6;
+		else
+			goto _out;
+
+		baud = 0;
+		while (*s >= '0' && *s <= '9')
+			baud = baud * 10 + *s++ - '0';
+	}
+
+_out:
+	return baud;
+}
+
+void __init fw_init_early_console(char port)
+{
+	char *arch_cmdline = pic32_getcmdline();
+	int baud = -1;
+
+	uart_base = ioremap_nocache(PIC32_BASE_UART, 0xc00);
+
+	baud = get_baud_from_cmdline(arch_cmdline);
+	if (port == -1)
+		port = get_port_from_cmdline(arch_cmdline);
+
+	if (port == -1)
+		port = EARLY_CONSOLE_PORT;
+
+	if (baud == -1)
+		baud = EARLY_CONSOLE_BAUDRATE;
+
+	setup_early_console(port, baud);
+}
+
+int prom_putchar(char c)
+{
+	if (console_port >= 0) {
+		while (__raw_readl(
+				uart_base + U_STA(console_port)) & UART_TX_FULL)
+			;
+
+		__raw_writel(c, uart_base + U_TXR(console_port));
+	}
+
+	return 1;
+}