lib: utils: serial: Add Cadence UART driver

Add Cadence UART driver

Signed-off-by: Jun Liang Tan <junliang.tan@linux.starfivetech.com>
Signed-off-by: Wei Liang Lim <weiliang.lim@linux.starfivetech.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

include/sbi_utils/fdt/fdt_helper.h

@@ -65,8 +65,8 @@ int fdt_parse_shakti_uart_node(void *fdt, int nodeoffset,
 int fdt_parse_sifive_uart_node(void *fdt, int nodeoffset,
 			       struct platform_uart_data *uart);
 
-int fdt_parse_uart8250_node(void *fdt, int nodeoffset,
+int fdt_parse_uart_node(void *fdt, int nodeoffset,
-			    struct platform_uart_data *uart);
+			struct platform_uart_data *uart);
 
 int fdt_parse_uart8250(void *fdt, struct platform_uart_data *uart,
 		       const char *compatible);

include/sbi_utils/serial/cadence-uart.h

@@ -0,0 +1,16 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 StarFive Technology Co., Ltd.
+ *
+ * Author: Jun Liang Tan <junliang.tan@linux.starfivetech.com>
+ */
+
+#ifndef __SERIAL_CADENCE_UART_H__
+#define __SERIAL_CADENCE_UART_H__
+
+#include <sbi/sbi_types.h>
+
+int cadence_uart_init(unsigned long base, u32 in_freq, u32 baudrate);
+
+#endif

lib/utils/fdt/fdt_helper.c

@@ -401,8 +401,8 @@ int fdt_parse_sifive_uart_node(void *fdt, int nodeoffset,
 	return 0;
 }
 
-int fdt_parse_uart8250_node(void *fdt, int nodeoffset,
+int fdt_parse_uart_node(void *fdt, int nodeoffset,
-			    struct platform_uart_data *uart)
+			struct platform_uart_data *uart)
 {
 	int len, rc;
 	const fdt32_t *val;
@@ -447,7 +447,7 @@ int fdt_parse_uart8250(void *fdt, struct platform_uart_data *uart,
 	if (nodeoffset < 0)
 		return nodeoffset;
 
-	return fdt_parse_uart8250_node(fdt, nodeoffset, uart);
+	return fdt_parse_uart_node(fdt, nodeoffset, uart);
 }
 
 int fdt_parse_xlnx_uartlite_node(void *fdt, int nodeoffset,

lib/utils/serial/Kconfig

@@ -9,6 +9,11 @@ config FDT_SERIAL
 
 if FDT_SERIAL
 
+config FDT_SERIAL_CADENCE
+	bool "Cadence UART FDT driver"
+	select SERIAL_CADENCE
+	default n
+
 config FDT_SERIAL_GAISLER
 	bool "Gaisler UART FDT driver"
 	select SERIAL_GAISLER
@@ -46,6 +51,10 @@ config FDT_SERIAL_XILINX_UARTLITE
 
 endif
 
+config SERIAL_CADENCE
+	bool "Cadence UART support"
+	default n
+
 config SERIAL_GAISLER
 	bool "Gaisler UART support"
 	default n

lib/utils/serial/cadence-uart.c

@@ -0,0 +1,128 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 StarFive Technology Co., Ltd.
+ *
+ * Author: Jun Liang Tan <junliang.tan@linux.starfivetech.com>
+ */
+
+#include <sbi/riscv_io.h>
+#include <sbi/sbi_console.h>
+#include <sbi_utils/serial/cadence-uart.h>
+
+/* clang-format off */
+
+#define UART_REG_CTRL		0x00
+#define UART_REG_MODE		0x04
+#define UART_REG_IDR		0x0C
+#define UART_REG_BRGR		0x18
+#define UART_REG_CSR		0x2C
+#define UART_REG_RFIFO_TFIFO	0x30
+#define UART_REG_BDIVR		0x34
+
+#define UART_CTRL_RXRES		0x00000001
+#define UART_CTRL_TXRES		0x00000002
+#define UART_CTRL_RXEN		0x00000004
+#define UART_CTRL_RXDIS		0x00000008
+#define UART_CTRL_TXEN		0x00000010
+#define UART_CTRL_TXDIS		0x00000020
+
+#define UART_MODE_PAR_NONE	0x00000020	/* No parity set */
+
+#define UART_BRGR_CD_CLKDIVISOR	0x00000001	/* baud_sample = sel_clk */
+
+#define	UART_CSR_REMPTY		0x00000002
+#define	UART_CSR_TFUL		0x00000010
+
+/* clang-format on */
+
+static volatile void *uart_base;
+static u32 uart_in_freq;
+static u32 uart_baudrate;
+
+/*
+ * Find minimum divisor divides in_freq to max_target_hz;
+ * Based on SiFive UART driver (sifive-uart.c)
+ */
+static inline unsigned int uart_min_clk_divisor(uint64_t in_freq,
+						uint64_t max_target_hz)
+{
+	uint64_t quotient = (in_freq + max_target_hz - 1) / (max_target_hz);
+
+	/* Avoid underflow */
+	if (quotient == 0)
+		return 0;
+	else
+		return quotient - 1;
+}
+
+static u32 get_reg(u32 offset)
+{
+	return readl(uart_base + offset);
+}
+
+static void set_reg(u32 offset, u32 val)
+{
+	writel(val, uart_base + offset);
+}
+
+static void cadence_uart_putc(char ch)
+{
+	while (get_reg(UART_REG_CSR) & UART_CSR_TFUL)
+		;
+
+	set_reg(UART_REG_RFIFO_TFIFO, ch);
+}
+
+static int cadence_uart_getc(void)
+{
+	u32 ret = get_reg(UART_REG_CSR);
+
+	if (!(ret & UART_CSR_REMPTY))
+		return get_reg(UART_REG_RFIFO_TFIFO);
+
+	return -1;
+}
+
+static struct sbi_console_device cadence_console = {
+	.name = "cadence_uart",
+	.console_putc = cadence_uart_putc,
+	.console_getc = cadence_uart_getc
+};
+
+int cadence_uart_init(unsigned long base, u32 in_freq, u32 baudrate)
+{
+	uart_base     = (volatile void *)base;
+	uart_in_freq  = in_freq;
+	uart_baudrate = baudrate;
+
+	/* Disable interrupts */
+	set_reg(UART_REG_IDR, 0xFFFFFFFF);
+
+	/* Disable TX RX */
+	set_reg(UART_REG_CTRL, UART_CTRL_TXDIS | UART_CTRL_RXDIS);
+
+	/* Configure baudrate */
+	if (in_freq && baudrate) {
+		set_reg(UART_REG_BRGR, UART_BRGR_CD_CLKDIVISOR);
+		set_reg(UART_REG_BDIVR,
+			uart_min_clk_divisor(in_freq, baudrate));
+	}
+
+	/* Software reset TX RX data path and enable TX RX */
+	set_reg(UART_REG_CTRL, UART_CTRL_TXRES | UART_CTRL_RXRES
+		| UART_CTRL_TXEN | UART_CTRL_RXEN);
+
+	/*
+	 * Set:
+	 * 1 stop bit, bits[07:06] = 0x00,
+	 * no parity set, bits[05:03] = 0x100,
+	 * 8 bits character length, bits[02:01] = 0x00,
+	 * sel_clk = uart_clk, bit[0] = 0x0
+	 */
+	set_reg(UART_REG_MODE, UART_MODE_PAR_NONE);
+
+	sbi_console_set_device(&cadence_console);
+
+	return 0;
+}

lib/utils/serial/fdt_serial_cadence.c

@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 StarFive Technology Co., Ltd.
+ *
+ * Author: Jun Liang Tan <junliang.tan@linux.starfivetech.com>
+ */
+
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/serial/fdt_serial.h>
+#include <sbi_utils/serial/cadence-uart.h>
+
+static int serial_cadence_init(void *fdt, int nodeoff,
+			       const struct fdt_match *match)
+{
+	int rc;
+	struct platform_uart_data uart = { 0 };
+
+	rc = fdt_parse_uart_node(fdt, nodeoff, &uart);
+	if (rc)
+		return rc;
+
+	return cadence_uart_init(uart.addr, uart.freq, uart.baud);
+}
+
+static const struct fdt_match serial_cadence_match[] = {
+	{ .compatible = "cdns,uart-r1p12" },
+	{ .compatible = "starfive,jh8100-uart" },
+	{ },
+};
+
+struct fdt_serial fdt_serial_cadence = {
+	.match_table = serial_cadence_match,
+	.init = serial_cadence_init
+};

lib/utils/serial/fdt_serial_uart8250.c

@@ -17,7 +17,7 @@ static int serial_uart8250_init(void *fdt, int nodeoff,
 	int rc;
 	struct platform_uart_data uart = { 0 };
 
-	rc = fdt_parse_uart8250_node(fdt, nodeoff, &uart);
+	rc = fdt_parse_uart_node(fdt, nodeoff, &uart);
 	if (rc)
 		return rc;
 

lib/utils/serial/objects.mk

@@ -10,6 +10,9 @@
 libsbiutils-objs-$(CONFIG_FDT_SERIAL) += serial/fdt_serial.o
 libsbiutils-objs-$(CONFIG_FDT_SERIAL) += serial/fdt_serial_drivers.o
 
+carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_CADENCE) += fdt_serial_cadence
+libsbiutils-objs-$(CONFIG_FDT_SERIAL_CADENCE) += serial/fdt_serial_cadence.o
+
 carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_GAISLER) += fdt_serial_gaisler
 libsbiutils-objs-$(CONFIG_FDT_SERIAL_GAISLER) += serial/fdt_serial_gaisler.o
 
@@ -31,6 +34,7 @@ libsbiutils-objs-$(CONFIG_FDT_SERIAL_UART8250) += serial/fdt_serial_uart8250.o
 carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_XILINX_UARTLITE) += fdt_serial_xlnx_uartlite
 libsbiutils-objs-$(CONFIG_FDT_SERIAL_XILINX_UARTLITE) += serial/fdt_serial_xlnx_uartlite.o
 
+libsbiutils-objs-$(CONFIG_SERIAL_CADENCE) += serial/cadence-uart.o
 libsbiutils-objs-$(CONFIG_SERIAL_GAISLER) += serial/gaisler-uart.o
 libsbiutils-objs-$(CONFIG_SERIAL_SHAKTI) += serial/shakti-uart.o
 libsbiutils-objs-$(CONFIG_SERIAL_SIFIVE) += serial/sifive-uart.o

platform/generic/configs/defconfig

@@ -18,6 +18,7 @@ CONFIG_FDT_RESET_SIFIVE_TEST=y
 CONFIG_FDT_RESET_SUNXI_WDT=y
 CONFIG_FDT_RESET_THEAD=y
 CONFIG_FDT_SERIAL=y
+CONFIG_FDT_SERIAL_CADENCE=y
 CONFIG_FDT_SERIAL_GAISLER=y
 CONFIG_FDT_SERIAL_HTIF=y
 CONFIG_FDT_SERIAL_SHAKTI=y