[PATCH 2/5] serial: s5p: Add Apple M1 support

[Mark Kettenis <kettenis@openbsd.org>]

Apple M1 SoCs include an S5L UART which is a variant of the S5P
UART.  Add support for this variant and enable it by default
on Apple SoCs.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
---
 arch/arm/include/asm/arch-m1/clk.h  | 11 ++++++++
 arch/arm/include/asm/arch-m1/uart.h | 41 +++++++++++++++++++++++++++++
 arch/arm/mach-apple/board.c         |  5 ++++
 drivers/serial/Kconfig              |  2 +-
 drivers/serial/serial_s5p.c         | 22 ++++++++++++++++
 5 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm/include/asm/arch-m1/clk.h
 create mode 100644 arch/arm/include/asm/arch-m1/uart.h

diff --git a/arch/arm/include/asm/arch-m1/clk.h b/arch/arm/include/asm/arch-m1/clk.h
new file mode 100644
index 0000000000..f4326d0c0f
--- /dev/null
+++ b/arch/arm/include/asm/arch-m1/clk.h
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
+ */
+
+#ifndef __ASM_ARM_ARCH_CLK_H_
+#define __ASM_ARM_ARCH_CLK_H_
+
+unsigned long get_uart_clk(int dev_index);
+
+#endif
diff --git a/arch/arm/include/asm/arch-m1/uart.h b/arch/arm/include/asm/arch-m1/uart.h
new file mode 100644
index 0000000000..d2a17a221e
--- /dev/null
+++ b/arch/arm/include/asm/arch-m1/uart.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2009 Samsung Electronics
+ * Minkyu Kang <mk7.kang@samsung.com>
+ * Heungjun Kim <riverful.kim@samsung.com>
+ */
+
+#ifndef __ASM_ARCH_UART_H_
+#define __ASM_ARCH_UART_H_
+
+#ifndef __ASSEMBLY__
+/* baudrate rest value */
+union br_rest {
+	unsigned short	slot;		/* udivslot */
+	unsigned char	value;		/* ufracval */
+};
+
+struct s5p_uart {
+	unsigned int	ulcon;
+	unsigned int	ucon;
+	unsigned int	ufcon;
+	unsigned int	umcon;
+	unsigned int	utrstat;
+	unsigned int	uerstat;
+	unsigned int	ufstat;
+	unsigned int	umstat;
+	unsigned int	utxh;
+	unsigned int	urxh;
+	unsigned int	ubrdiv;
+	union br_rest	rest;
+	unsigned char	res3[0x3fd0];
+};
+
+static inline int s5p_uart_divslot(void)
+{
+	return 0;
+}
+
+#endif	/* __ASSEMBLY__ */
+
+#endif
diff --git a/arch/arm/mach-apple/board.c b/arch/arm/mach-apple/board.c
index 0c8b35292e..8bc5c2f69e 100644
--- a/arch/arm/mach-apple/board.c
+++ b/arch/arm/mach-apple/board.c
@@ -156,3 +156,8 @@ ulong board_get_usable_ram_top(ulong total_size)
 	 */
 	return 0x980000000;
 }
+
+unsigned long get_uart_clk(int dev_index)
+{
+	return 24000000;
+}
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 93348c0929..c3ac773929 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -719,7 +719,7 @@ config ROCKCHIP_SERIAL
 
 config S5P_SERIAL
 	bool "Support for Samsung S5P UART"
-	depends on ARCH_EXYNOS || ARCH_S5PC1XX
+	depends on ARCH_APPLE || ARCH_EXYNOS || ARCH_S5PC1XX
 	default y
 	help
 	  Select this to enable Samsung S5P UART support.
diff --git a/drivers/serial/serial_s5p.c b/drivers/serial/serial_s5p.c
index 6d09952a5d..eb770d9b62 100644
--- a/drivers/serial/serial_s5p.c
+++ b/drivers/serial/serial_s5p.c
@@ -21,12 +21,21 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#ifdef CONFIG_ARCH_APPLE
+#define RX_FIFO_COUNT_SHIFT	0
+#define RX_FIFO_COUNT_MASK	(0xf << RX_FIFO_COUNT_SHIFT)
+#define RX_FIFO_FULL		(1 << 8)
+#define TX_FIFO_COUNT_SHIFT	4
+#define TX_FIFO_COUNT_MASK	(0xf << TX_FIFO_COUNT_SHIFT)
+#define TX_FIFO_FULL		(1 << 9)
+#else
 #define RX_FIFO_COUNT_SHIFT	0
 #define RX_FIFO_COUNT_MASK	(0xff << RX_FIFO_COUNT_SHIFT)
 #define RX_FIFO_FULL		(1 << 8)
 #define TX_FIFO_COUNT_SHIFT	16
 #define TX_FIFO_COUNT_MASK	(0xff << TX_FIFO_COUNT_SHIFT)
 #define TX_FIFO_FULL		(1 << 24)
+#endif
 
 /* Information about a serial port */
 struct s5p_serial_plat {
@@ -83,7 +92,11 @@ static void __maybe_unused s5p_serial_baud(struct s5p_uart *uart, uint uclk,
 	if (s5p_uart_divslot())
 		writew(udivslot[val % 16], &uart->rest.slot);
 	else
+#ifdef CONFIG_ARCH_APPLE
+		writel(val % 16, &uart->rest.value);
+#else
 		writeb(val % 16, &uart->rest.value);
+#endif
 }
 
 #ifndef CONFIG_SPL_BUILD
@@ -148,7 +161,11 @@ static int s5p_serial_getc(struct udevice *dev)
 		return -EAGAIN;
 
 	serial_err_check(uart, 0);
+#ifdef CONFIG_ARCH_APPLE
+	return (int)(readl(&uart->urxh) & 0xff);
+#else
 	return (int)(readb(&uart->urxh) & 0xff);
+#endif
 }
 
 static int s5p_serial_putc(struct udevice *dev, const char ch)
@@ -159,7 +176,11 @@ static int s5p_serial_putc(struct udevice *dev, const char ch)
 	if (readl(&uart->ufstat) & TX_FIFO_FULL)
 		return -EAGAIN;
 
+#ifdef CONFIG_ARCH_APPLE
+	writel(ch, &uart->utxh);
+#else
 	writeb(ch, &uart->utxh);
+#endif
 	serial_err_check(uart, 1);
 
 	return 0;
@@ -201,6 +222,7 @@ static const struct dm_serial_ops s5p_serial_ops = {
 
 static const struct udevice_id s5p_serial_ids[] = {
 	{ .compatible = "samsung,exynos4210-uart" },
+	{ .compatible = "apple,s5l-uart" },
 	{ }
 };
 
-- 
2.33.0