dm: serial: Add driver model support for ns16550

Add driver model support so that ns16550 can support operation both with
and without driver model.

The driver needs a clock frequency so cannot stand alone unfortunately. The
clock frequency must be provided by a separate driver.

Signed-off-by: Simon Glass <sjg@chromium.org>

doc/device-tree-bindings/serial/ns16550.txt

@@ -0,0 +1,10 @@
+NS16550 UART
+
+This UART driver supports many chip variants and is used in mamy SoCs.
+
+Required properties:
+- compatible: "ns16550" or "nvidia,tegra20-uart"
+- reg: start address and size of registers
+- reg-shift: shift value indicating register size: 0=byte, 1=16bit,2=32bit etc.
+- clock-frequency: input clock frequency for the UART (used to calculate the
+    baud rate divisor)

drivers/serial/Makefile

@@ -9,6 +9,7 @@ ifdef CONFIG_DM_SERIAL
 obj-y += serial-uclass.o
 else
 obj-y += serial.o
+obj-$(CONFIG_SYS_NS16550_SERIAL) += serial_ns16550.o
 endif
 
 obj-$(CONFIG_ALTERA_UART) += altera_uart.o
@@ -20,7 +21,6 @@ obj-$(CONFIG_MCFUART) += mcfuart.o
 obj-$(CONFIG_OPENCORES_YANU) += opencores_yanu.o
 obj-$(CONFIG_SYS_NS16550) += ns16550.o
 obj-$(CONFIG_S5P) += serial_s5p.o
-obj-$(CONFIG_SYS_NS16550_SERIAL) += serial_ns16550.o
 obj-$(CONFIG_IMX_SERIAL) += serial_imx.o
 obj-$(CONFIG_KS8695_SERIAL) += serial_ks8695.o
 obj-$(CONFIG_MAX3100_SERIAL) += serial_max3100.o

drivers/serial/ns16550.c

@@ -5,17 +5,25 @@
  */
 
 #include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
 #include <ns16550.h>
+#include <serial.h>
 #include <watchdog.h>
 #include <linux/types.h>
 #include <asm/io.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 #define UART_LCRVAL UART_LCR_8N1		/* 8 data, 1 stop, no parity */
 #define UART_MCRVAL (UART_MCR_DTR | \
 		     UART_MCR_RTS)		/* RTS/DTR */
 #define UART_FCRVAL (UART_FCR_FIFO_EN |	\
 		     UART_FCR_RXSR |	\
 		     UART_FCR_TXSR)		/* Clear & enable FIFOs */
+
+#ifndef CONFIG_DM_SERIAL
 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
 #define serial_out(x, y)	outb(x, (ulong)y)
 #define serial_in(y)		inb((ulong)y)
@@ -29,6 +37,7 @@
 #define serial_out(x, y)	writeb(x, y)
 #define serial_in(y)		readb(y)
 #endif
+#endif /* !CONFIG_DM_SERIAL */
 
 #if defined(CONFIG_SOC_KEYSTONE)
 #define UART_REG_VAL_PWREMU_MGMT_UART_DISABLE   0
@@ -45,6 +54,58 @@
 #define CONFIG_SYS_NS16550_IER  0x00
 #endif /* CONFIG_SYS_NS16550_IER */
 
+#ifdef CONFIG_DM_SERIAL
+static void ns16550_writeb(NS16550_t port, int offset, int value)
+{
+	struct ns16550_platdata *plat = port->plat;
+	unsigned char *addr;
+
+	offset *= 1 << plat->reg_shift;
+	addr = plat->base + offset;
+	/*
+	 * As far as we know it doesn't make sense to support selection of
+	 * these options at run-time, so use the existing CONFIG options.
+	 */
+#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
+	outb(value, addr);
+#elif defined(CONFIG_SYS_NS16550_MEM32) && !defined(CONFIG_SYS_BIG_ENDIAN)
+	out_le32(addr, value);
+#elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_BIG_ENDIAN)
+	out_be32(addr, value);
+#elif defined(CONFIG_SYS_BIG_ENDIAN)
+	writeb(value, addr + (1 << plat->reg_shift) - 1);
+#else
+	writeb(value, addr);
+#endif
+}
+
+static int ns16550_readb(NS16550_t port, int offset)
+{
+	struct ns16550_platdata *plat = port->plat;
+	unsigned char *addr;
+
+	offset *= 1 << plat->reg_shift;
+	addr = plat->base + offset;
+#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
+	return inb(addr);
+#elif defined(CONFIG_SYS_NS16550_MEM32) && !defined(CONFIG_SYS_BIG_ENDIAN)
+	return in_le32(addr);
+#elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_BIG_ENDIAN)
+	return in_be32(addr);
+#elif defined(CONFIG_SYS_BIG_ENDIAN)
+	return readb(addr + (1 << plat->reg_shift) - 1);
+#else
+	return readb(addr);
+#endif
+}
+
+/* We can clean these up once everything is moved to driver model */
+#define serial_out(value, addr)	\
+	ns16550_writeb(com_port, addr - (unsigned char *)com_port, value)
+#define serial_in(addr) \
+	ns16550_readb(com_port, addr - (unsigned char *)com_port)
+#endif
+
 int ns16550_calc_divisor(NS16550_t port, int clock, int baudrate)
 {
 	const unsigned int mode_x_div = 16;
@@ -79,7 +140,8 @@ void NS16550_init(NS16550_t com_port, int baud_divisor)
 	 */
 	if ((serial_in(&com_port->lsr) & (UART_LSR_TEMT | UART_LSR_THRE))
 	     == UART_LSR_THRE) {
-		NS16550_setbrg(com_port, baud_divisor);
+		if (baud_divisor != -1)
+			NS16550_setbrg(com_port, baud_divisor);
 		serial_out(0, &com_port->mdr1);
 	}
 #endif
@@ -95,7 +157,8 @@ void NS16550_init(NS16550_t com_port, int baud_divisor)
 	NS16550_setbrg(com_port, 0);
 	serial_out(UART_MCRVAL, &com_port->mcr);
 	serial_out(UART_FCRVAL, &com_port->fcr);
-	NS16550_setbrg(com_port, baud_divisor);
+	if (baud_divisor != -1)
+		NS16550_setbrg(com_port, baud_divisor);
 #if defined(CONFIG_OMAP) || \
 	defined(CONFIG_AM33XX) || defined(CONFIG_SOC_DA8XX) || \
 	defined(CONFIG_TI81XX) || defined(CONFIG_AM43XX)
@@ -154,3 +217,92 @@ int NS16550_tstc(NS16550_t com_port)
 }
 
 #endif /* CONFIG_NS16550_MIN_FUNCTIONS */
+
+#ifdef CONFIG_DM_SERIAL
+static int ns16550_serial_putc(struct udevice *dev, const char ch)
+{
+	struct NS16550 *const com_port = dev_get_priv(dev);
+
+	if (!(serial_in(&com_port->lsr) & UART_LSR_THRE))
+		return -EAGAIN;
+	serial_out(ch, &com_port->thr);
+
+	/*
+	 * Call watchdog_reset() upon newline. This is done here in putc
+	 * since the environment code uses a single puts() to print the complete
+	 * environment upon "printenv". So we can't put this watchdog call
+	 * in puts().
+	 */
+	if (ch == '\n')
+		WATCHDOG_RESET();
+
+	return 0;
+}
+
+static int ns16550_serial_pending(struct udevice *dev, bool input)
+{
+	struct NS16550 *const com_port = dev_get_priv(dev);
+
+	if (input)
+		return serial_in(&com_port->lsr) & UART_LSR_DR ? 1 : 0;
+	else
+		return serial_in(&com_port->lsr) & UART_LSR_THRE ? 0 : 1;
+}
+
+static int ns16550_serial_getc(struct udevice *dev)
+{
+	struct NS16550 *const com_port = dev_get_priv(dev);
+
+	if (!serial_in(&com_port->lsr) & UART_LSR_DR)
+		return -EAGAIN;
+
+	return serial_in(&com_port->rbr);
+}
+
+static int ns16550_serial_setbrg(struct udevice *dev, int baudrate)
+{
+	struct NS16550 *const com_port = dev_get_priv(dev);
+	struct ns16550_platdata *plat = com_port->plat;
+	int clock_divisor;
+
+	clock_divisor = ns16550_calc_divisor(com_port, plat->clock, baudrate);
+
+	NS16550_setbrg(com_port, clock_divisor);
+
+	return 0;
+}
+
+int ns16550_serial_probe(struct udevice *dev)
+{
+	struct NS16550 *const com_port = dev_get_priv(dev);
+
+	NS16550_init(com_port, -1);
+
+	return 0;
+}
+
+int ns16550_serial_ofdata_to_platdata(struct udevice *dev)
+{
+	struct NS16550 *const com_port = dev_get_priv(dev);
+	struct ns16550_platdata *plat = dev->platdata;
+	fdt_addr_t addr;
+
+	addr = fdtdec_get_addr(gd->fdt_blob, dev->of_offset, "reg");
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	plat->base = (unsigned char *)addr;
+	plat->reg_shift = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
+					 "reg-shift", 1);
+	com_port->plat = plat;
+
+	return 0;
+}
+
+const struct dm_serial_ops ns16550_serial_ops = {
+	.putc = ns16550_serial_putc,
+	.pending = ns16550_serial_pending,
+	.getc = ns16550_serial_getc,
+	.setbrg = ns16550_serial_setbrg,
+};
+#endif /* CONFIG_DM_SERIAL */

include/ns16550.h

@@ -23,6 +23,14 @@
 
 #include <linux/types.h>
 
+#ifdef CONFIG_DM_SERIAL
+/*
+ * For driver model we always use one byte per register, and sort out the
+ * differences in the driver
+ */
+#define CONFIG_SYS_NS16550_REG_SIZE (-1)
+#endif
+
 #if !defined(CONFIG_SYS_NS16550_REG_SIZE) || (CONFIG_SYS_NS16550_REG_SIZE == 0)
 #error "Please define NS16550 registers size."
 #elif defined(CONFIG_SYS_NS16550_MEM32)
@@ -37,6 +45,21 @@
 	unsigned char postpad_##x[-CONFIG_SYS_NS16550_REG_SIZE - 1];
 #endif
 
+/**
+ * struct ns16550_platdata - information about a NS16550 port
+ *
+ * @base:		Base register address
+ * @reg_shift:		Shift size of registers (0=byte, 1=16bit, 2=32bit...)
+ * @clock:		UART base clock speed in Hz
+ */
+struct ns16550_platdata {
+	unsigned char *base;
+	int reg_shift;
+	int clock;
+};
+
+struct udevice;
+
 struct NS16550 {
 	UART_REG(rbr);		/* 0 */
 	UART_REG(ier);		/* 1 */
@@ -65,6 +88,9 @@ struct NS16550 {
 	UART_REG(scr);		/* 10*/
 	UART_REG(ssr);		/* 11*/
 #endif
+#ifdef CONFIG_DM_SERIAL
+	struct ns16550_platdata *plat;
+#endif
 };
 
 #define thr rbr
@@ -183,3 +209,30 @@ void NS16550_reinit(NS16550_t com_port, int baud_divisor);
  * @return baud rate divisor that should be used
  */
 int ns16550_calc_divisor(NS16550_t port, int clock, int baudrate);
+
+/**
+ * ns16550_serial_ofdata_to_platdata() - convert DT to platform data
+ *
+ * Decode a device tree node for an ns16550 device. This includes the
+ * register base address and register shift properties. The caller must set
+ * up the clock frequency.
+ *
+ * @dev:	dev to decode platform data for
+ * @return:	0 if OK, -EINVAL on error
+ */
+int ns16550_serial_ofdata_to_platdata(struct udevice *dev);
+
+/**
+ * ns16550_serial_probe() - probe a serial port
+ *
+ * This sets up the serial port ready for use, except for the baud rate
+ * @return 0, or -ve on error
+ */
+int ns16550_serial_probe(struct udevice *dev);
+
+/**
+ * struct ns16550_serial_ops - ns16550 serial operations
+ *
+ * These should be used by the client driver for the driver's 'ops' member
+ */
+extern const struct dm_serial_ops ns16550_serial_ops;