drivers: serial: add serial driver for ar933x SOC

This patch add support for ar933x serial.

Signed-off-by: Wills Wang <wills.wang@live.com>
Reviewed-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

doc/device-tree-bindings/serial/qca,ar9330-uart.txt

+* Qualcomm Atheros AR9330 High-Speed UART
+
+Required properties:
+
+- compatible: Must be "qca,ar9330-uart"
+
+- reg: Specifies the physical base address of the controller and
+  the length of the memory mapped region.
+
+Additional requirements:
+
+  Each UART port must have an alias correctly numbered in "aliases"
+  node.
+
+Example:
+
+	aliases {
+		serial0 = &uart0;
+	};
+
+	uart0: uart@18020000 {
+		compatible = "qca,ar9330-uart";
+		reg = <0x18020000 0x14>;
+	};

drivers/serial/Kconfig

@@ -89,6 +89,15 @@ config DEBUG_UART_ALTERA_UART
 	  You will need to provide parameters to make this work. The driver will
 	  be available until the real driver model serial is running.
 
+config DEBUG_UART_AR933X
+	bool "QCA/Atheros ar933x"
+	depends on AR933X_UART
+	help
+	  Select this to enable a debug UART using the ar933x uart driver.
+	  You will need to provide parameters to make this work. The
+	  driver will be available until the real driver model serial is
+	  running.
+
 config DEBUG_UART_NS16550
 	bool "ns16550"
 	help
@@ -263,6 +272,15 @@ config ALTERA_UART
 	  Select this to enable an UART for Altera devices. Please find
 	  details on the "Embedded Peripherals IP User Guide" of Altera.
 
+config AR933X_UART
+	bool "QCA/Atheros ar933x UART support"
+	depends on DM_SERIAL && SOC_AR933X
+	help
+	  Select this to enable UART support for QCA/Atheros ar933x
+	  devices. This driver uses driver model and requires a device
+	  tree binding to operate, please refer to the document at
+	  doc/device-tree-bindings/serial/qca,ar9330-uart.txt.
+
 config FSL_LPUART
 	bool "Freescale LPUART support"
 	help

drivers/serial/Makefile

@@ -17,6 +17,7 @@ endif
 
 obj-$(CONFIG_ALTERA_UART) += altera_uart.o
 obj-$(CONFIG_ALTERA_JTAG_UART) += altera_jtag_uart.o
+obj-$(CONFIG_AR933X_UART) += serial_ar933x.o
 obj-$(CONFIG_ARM_DCC) += arm_dcc.o
 obj-$(CONFIG_ATMEL_USART) += atmel_usart.o
 obj-$(CONFIG_EFI_APP) += serial_efi.o

drivers/serial/serial_ar933x.c

+/*
+ * Copyright (C) 2015-2016 Wills Wang <wills.wang@live.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <div64.h>
+#include <errno.h>
+#include <serial.h>
+#include <asm/io.h>
+#include <asm/addrspace.h>
+#include <asm/types.h>
+#include <dm/pinctrl.h>
+#include <mach/ar71xx_regs.h>
+
+#define AR933X_UART_DATA_REG            0x00
+#define AR933X_UART_CS_REG              0x04
+#define AR933X_UART_CLK_REG             0x08
+
+#define AR933X_UART_DATA_TX_RX_MASK     0xff
+#define AR933X_UART_DATA_RX_CSR         BIT(8)
+#define AR933X_UART_DATA_TX_CSR         BIT(9)
+#define AR933X_UART_CS_IF_MODE_S        2
+#define AR933X_UART_CS_IF_MODE_M        0x3
+#define AR933X_UART_CS_IF_MODE_DTE      1
+#define AR933X_UART_CS_IF_MODE_DCE      2
+#define AR933X_UART_CS_TX_RDY_ORIDE     BIT(7)
+#define AR933X_UART_CS_RX_RDY_ORIDE     BIT(8)
+#define AR933X_UART_CLK_STEP_M          0xffff
+#define AR933X_UART_CLK_SCALE_M         0xfff
+#define AR933X_UART_CLK_SCALE_S         16
+#define AR933X_UART_CLK_STEP_S          0
+
+struct ar933x_serial_priv {
+	void __iomem *regs;
+};
+
+/*
+ * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
+ */
+static u32 ar933x_serial_get_baud(u32 clk, u32 scale, u32 step)
+{
+	u64 t;
+	u32 div;
+
+	div = (2 << 16) * (scale + 1);
+	t = clk;
+	t *= step;
+	t += (div / 2);
+	do_div(t, div);
+
+	return t;
+}
+
+static void ar933x_serial_get_scale_step(u32 clk, u32 baud,
+					 u32 *scale, u32 *step)
+{
+	u32 tscale, baudrate;
+	long min_diff;
+
+	*scale = 0;
+	*step = 0;
+
+	min_diff = baud;
+	for (tscale = 0; tscale < AR933X_UART_CLK_SCALE_M; tscale++) {
+		u64 tstep;
+		int diff;
+
+		tstep = baud * (tscale + 1);
+		tstep *= (2 << 16);
+		do_div(tstep, clk);
+
+		if (tstep > AR933X_UART_CLK_STEP_M)
+			break;
+
+		baudrate = ar933x_serial_get_baud(clk, tscale, tstep);
+		diff = abs(baudrate - baud);
+		if (diff < min_diff) {
+			min_diff = diff;
+			*scale = tscale;
+			*step = tstep;
+		}
+	}
+}
+
+static int ar933x_serial_setbrg(struct udevice *dev, int baudrate)
+{
+	struct ar933x_serial_priv *priv = dev_get_priv(dev);
+	u32 val, scale, step;
+
+	val = get_serial_clock();
+	ar933x_serial_get_scale_step(val, baudrate, &scale, &step);
+
+	val  = (scale & AR933X_UART_CLK_SCALE_M)
+			<< AR933X_UART_CLK_SCALE_S;
+	val |= (step & AR933X_UART_CLK_STEP_M)
+			<< AR933X_UART_CLK_STEP_S;
+	writel(val, priv->regs + AR933X_UART_CLK_REG);
+
+	return 0;
+}
+
+static int ar933x_serial_putc(struct udevice *dev, const char c)
+{
+	struct ar933x_serial_priv *priv = dev_get_priv(dev);
+	u32 data;
+
+	data = readl(priv->regs + AR933X_UART_DATA_REG);
+	if (!(data & AR933X_UART_DATA_TX_CSR))
+		return -EAGAIN;
+
+	data  = (u32)c | AR933X_UART_DATA_TX_CSR;
+	writel(data, priv->regs + AR933X_UART_DATA_REG);
+
+	return 0;
+}
+
+static int ar933x_serial_getc(struct udevice *dev)
+{
+	struct ar933x_serial_priv *priv = dev_get_priv(dev);
+	u32 data;
+
+	data = readl(priv->regs + AR933X_UART_DATA_REG);
+	if (!(data & AR933X_UART_DATA_RX_CSR))
+		return -EAGAIN;
+
+	writel(AR933X_UART_DATA_RX_CSR, priv->regs + AR933X_UART_DATA_REG);
+	return data & AR933X_UART_DATA_TX_RX_MASK;
+}
+
+static int ar933x_serial_pending(struct udevice *dev, bool input)
+{
+	struct ar933x_serial_priv *priv = dev_get_priv(dev);
+	u32 data;
+
+	data = readl(priv->regs + AR933X_UART_DATA_REG);
+	if (input)
+		return (data & AR933X_UART_DATA_RX_CSR) ? 1 : 0;
+	else
+		return (data & AR933X_UART_DATA_TX_CSR) ? 0 : 1;
+}
+
+static int ar933x_serial_probe(struct udevice *dev)
+{
+	struct ar933x_serial_priv *priv = dev_get_priv(dev);
+	struct udevice *pinctrl;
+	fdt_addr_t addr;
+	u32 val;
+	int ret;
+
+	ret = uclass_get_device(UCLASS_PINCTRL, 0, &pinctrl);
+	if (ret)
+		return ret;
+	ret = pinctrl_get_periph_id(pinctrl, dev);
+	if (ret < 0)
+		return ret;
+	ret = pinctrl_request(pinctrl, ret, 0);
+	if (ret < 0)
+		return ret;
+
+	addr = dev_get_addr(dev);
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	priv->regs = map_physmem(addr,
+				 AR933X_UART_SIZE,
+				 MAP_NOCACHE);
+
+	/*
+	 * UART controller configuration:
+	 * - no DMA
+	 * - no interrupt
+	 * - DCE mode
+	 * - no flow control
+	 * - set RX ready oride
+	 * - set TX ready oride
+	 */
+	val = (AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S) |
+	      AR933X_UART_CS_TX_RDY_ORIDE | AR933X_UART_CS_RX_RDY_ORIDE;
+	writel(val, priv->regs + AR933X_UART_CS_REG);
+	return 0;
+}
+
+static const struct dm_serial_ops ar933x_serial_ops = {
+	.putc = ar933x_serial_putc,
+	.pending = ar933x_serial_pending,
+	.getc = ar933x_serial_getc,
+	.setbrg = ar933x_serial_setbrg,
+};
+
+static const struct udevice_id ar933x_serial_ids[] = {
+	{ .compatible = "qca,ar9330-uart" },
+	{ }
+};
+
+U_BOOT_DRIVER(serial_ar933x) = {
+	.name   = "serial_ar933x",
+	.id = UCLASS_SERIAL,
+	.of_match = ar933x_serial_ids,
+	.priv_auto_alloc_size = sizeof(struct ar933x_serial_priv),
+	.probe = ar933x_serial_probe,
+	.ops    = &ar933x_serial_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};
+
+#ifdef CONFIG_DEBUG_UART_AR933X
+
+#include <debug_uart.h>
+
+static inline void _debug_uart_init(void)
+{
+	void __iomem *regs = (void *)CONFIG_DEBUG_UART_BASE;
+	u32 val, scale, step;
+
+	/*
+	 * UART controller configuration:
+	 * - no DMA
+	 * - no interrupt
+	 * - DCE mode
+	 * - no flow control
+	 * - set RX ready oride
+	 * - set TX ready oride
+	 */
+	val = (AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S) |
+	      AR933X_UART_CS_TX_RDY_ORIDE | AR933X_UART_CS_RX_RDY_ORIDE;
+	writel(val, regs + AR933X_UART_CS_REG);
+
+	ar933x_serial_get_scale_step(CONFIG_DEBUG_UART_CLOCK,
+				     CONFIG_BAUDRATE, &scale, &step);
+
+	val  = (scale & AR933X_UART_CLK_SCALE_M)
+			<< AR933X_UART_CLK_SCALE_S;
+	val |= (step & AR933X_UART_CLK_STEP_M)
+			<< AR933X_UART_CLK_STEP_S;
+	writel(val, regs + AR933X_UART_CLK_REG);
+}
+
+static inline void _debug_uart_putc(int c)
+{
+	void __iomem *regs = (void *)CONFIG_DEBUG_UART_BASE;
+	u32 data;
+
+	do {
+		data = readl(regs + AR933X_UART_DATA_REG);
+	} while (!(data & AR933X_UART_DATA_TX_CSR));
+
+	data  = (u32)c | AR933X_UART_DATA_TX_CSR;
+	writel(data, regs + AR933X_UART_DATA_REG);
+}
+
+DEBUG_UART_FUNCS
+
+#endif