serial: serial_cortina: add UART DM driver for CAxxxx SoCs

Add serial UART driver support for all Cortina Access
CAxxxx family of SoCs.

Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Signed-off-by: Jason Li <jason.li@cortina-access.com>
Signed-off-by: Alex Nemirovsky <alex.nemirovsky@cortina-access.com>

drivers/serial/Kconfig

@@ -553,6 +553,13 @@ config COREBOOT_SERIAL
 	  a serial console on any platform without needing to change the
 	  device tree, etc.
 
+config CORTINA_UART
+	bool "Cortina UART support"
+	depends on DM_SERIAL
+	help
+	  Select this to enable UART support for Cortina-Access UART devices
+	  found on CAxxxx SoCs.
+
 config FSL_LINFLEXUART
 	bool "Freescale Linflex UART support"
 	depends on DM_SERIAL

drivers/serial/Makefile

@@ -36,6 +36,7 @@ obj-$(CONFIG_ARM_DCC) += arm_dcc.o
 obj-$(CONFIG_ATMEL_USART) += atmel_usart.o
 obj-$(CONFIG_BCM6345_SERIAL) += serial_bcm6345.o
 obj-$(CONFIG_COREBOOT_SERIAL) += serial_coreboot.o
+obj-$(CONFIG_CORTINA_UART) += serial_cortina.o
 obj-$(CONFIG_EFI_APP) += serial_efi.o
 obj-$(CONFIG_LPC32XX_HSUART) += lpc32xx_hsuart.o
 obj-$(CONFIG_MCFUART) += mcfuart.o

drivers/serial/serial_cortina.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2020 Cortina-Access Ltd.
+ * Common UART Driver for Cortina Access CAxxxx line of SoCs
+ *
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <watchdog.h>
+#include <asm/io.h>
+#include <serial.h>
+#include <linux/compiler.h>
+
+/* Register definitions */
+#define UCFG			0x00	/* UART config register */
+#define UFC			0x04	/* Flow Control */
+#define URX_SAMPLE		0x08	/* UART RX Sample register */
+#define URT_TUNE		0x0C	/* Fine tune of UART clk */
+#define UTX_DATA		0x10	/* UART TX Character data */
+#define URX_DATA		0x14	/* UART RX Character data */
+#define UINFO			0x18	/* UART Info */
+#define UINT_EN0		0x1C	/* UART Interrupt enable 0 */
+#define UINT_EN1		0x20	/* UART Interrupt enable 1 */
+#define UINT0			0x24	/* UART Interrupt 0 setting/clearing */
+#define UINT1			0x28	/* UART Interrupt 1 setting/clearing */
+#define UINT_STAT		0x2C	/* UART Interrupt Status */
+
+/* UART Control Register Bit Fields */
+#define UCFG_BAUD_COUNT_MASK    0xFFFFFF00
+#define UCFG_BAUD_COUNT(x)	((x << 8) & UCFG_BAUD_COUNT_MASK)
+#define UCFG_EN			BIT(7)
+#define UCFG_RX_EN		BIT(6)
+#define UCFG_TX_EN		BIT(5)
+#define UCFG_PARITY_EN		BIT(4)
+#define UCFG_PARITY_SEL		BIT(3)
+#define UCFG_2STOP_BIT		BIT(2)
+#define UCFG_CNT1		BIT(1)
+#define UCFG_CNT0		BIT(0)
+#define UCFG_CHAR_5		0
+#define UCFG_CHAR_6		1
+#define UCFG_CHAR_7		2
+#define UCFG_CHAR_8		3
+
+#define UINFO_TX_FIFO_EMPTY	BIT(3)
+#define UINFO_TX_FIFO_FULL	BIT(2)
+#define UINFO_RX_FIFO_EMPTY	BIT(1)
+#define UINFO_RX_FIFO_FULL	BIT(0)
+
+#define UINT_RX_NON_EMPTY	BIT(6)
+#define UINT_TX_EMPTY		BIT(5)
+#define UINT_RX_UNDERRUN	BIT(4)
+#define UINT_RX_OVERRUN		BIT(3)
+#define UINT_RX_PARITY_ERR	BIT(2)
+#define UINT_RX_STOP_ERR	BIT(1)
+#define UINT_TX_OVERRUN		BIT(0)
+#define UINT_MASK_ALL		0x7F
+
+struct ca_uart_priv {
+	void __iomem *base;
+};
+
+int ca_serial_setbrg(struct udevice *dev, int baudrate)
+{
+	struct ca_uart_priv *priv = dev_get_priv(dev);
+	unsigned int uart_ctrl, baud, sample;
+
+	baud = CORTINA_UART_CLOCK / baudrate;
+
+	uart_ctrl = readl(priv->base + UCFG);
+	uart_ctrl &= ~UCFG_BAUD_COUNT_MASK;
+	uart_ctrl |= UCFG_BAUD_COUNT(baud);
+	writel(uart_ctrl, priv->base + UCFG);
+
+	sample = baud / 2;
+	sample = (sample < 7) ? 7 : sample;
+	writel(sample, priv->base + URX_SAMPLE);
+
+	return 0;
+}
+
+static int ca_serial_getc(struct udevice *dev)
+{
+	struct ca_uart_priv *priv = dev_get_priv(dev);
+	int ch;
+
+	ch = readl(priv->base + URX_DATA) & 0xFF;
+
+	return (int)ch;
+}
+
+static int ca_serial_putc(struct udevice *dev, const char ch)
+{
+	struct ca_uart_priv *priv = dev_get_priv(dev);
+	unsigned int status;
+
+	/* Retry if TX FIFO full */
+	status = readl(priv->base + UINFO);
+	if (status & UINFO_TX_FIFO_FULL)
+		return -EAGAIN;
+
+	writel(ch, priv->base + UTX_DATA);
+
+	return 0;
+}
+
+static int ca_serial_pending(struct udevice *dev, bool input)
+{
+	struct ca_uart_priv *priv = dev_get_priv(dev);
+	unsigned int status;
+
+	status = readl(priv->base + UINFO);
+
+	if (input)
+		return (status & UINFO_RX_FIFO_EMPTY) ? 0 : 1;
+	else
+		return (status & UINFO_TX_FIFO_FULL) ? 1 : 0;
+}
+
+static int ca_serial_probe(struct udevice *dev)
+{
+	struct ca_uart_priv *priv = dev_get_priv(dev);
+	u32 uart_ctrl;
+
+	/* Set data, parity and stop bits */
+	uart_ctrl = UCFG_EN | UCFG_TX_EN | UCFG_RX_EN | UCFG_CHAR_8;
+	writel(uart_ctrl, priv->base + UCFG);
+
+	return 0;
+}
+
+static int ca_serial_ofdata_to_platdata(struct udevice *dev)
+{
+	struct ca_uart_priv *priv = dev_get_priv(dev);
+
+	priv->base = dev_remap_addr_index(dev, 0);
+	if (!priv->base)
+		return -ENOENT;
+
+	return 0;
+}
+
+static const struct dm_serial_ops ca_serial_ops = {
+	.putc = ca_serial_putc,
+	.pending = ca_serial_pending,
+	.getc = ca_serial_getc,
+	.setbrg = ca_serial_setbrg,
+};
+
+static const struct udevice_id ca_serial_ids[] = {
+	{.compatible = "cortina,ca-uart"},
+	{}
+};
+
+U_BOOT_DRIVER(serial_cortina) = {
+	.name = "serial_cortina",
+	.id = UCLASS_SERIAL,
+	.of_match = ca_serial_ids,
+	.ofdata_to_platdata = ca_serial_ofdata_to_platdata,
+	.priv_auto_alloc_size = sizeof(struct ca_uart_priv),
+	.probe = ca_serial_probe,
+	.ops = &ca_serial_ops
+};