[U-Boot] [PATCH v3 06/14] drivers: serial: add driver for Microchip PIC32 UART controller.

Purna Chandra Mandal
2016-01-12T10:18:21Z

From: Paul Thacker <paul.thacker@microchip.com>

This adds PIC32 UART controller support based on driver model.

Signed-off-by: Paul Thacker <paul.thacker@microchip.com>
Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>

---

Changes in v3:
- remove ofdata_to_platdata, and replace platdata with priv
- remove special handling of '\r' as being handled by serial-uclass
- remove loop to wait for space in tx buffer before pumping char

Changes in v2:
- fix missing/corrupted chars during baud rate change
- remove loop until any char is avaialbale in getc()

.../serial/microchip,pic32-uart.txt | 5 +
drivers/serial/Kconfig | 13 ++
drivers/serial/Makefile | 1 +
drivers/serial/serial_pic32.c | 199 +++++++++++++++++++++
4 files changed, 218 insertions(+)
create mode 100644 doc/device-tree-bindings/serial/microchip,pic32-uart.txt
create mode 100644 drivers/serial/serial_pic32.c

diff --git a/doc/device-tree-bindings/serial/microchip,pic32-uart.txt b/doc/device-tree-bindings/serial/microchip,pic32-uart.txt
new file mode 100644
index 0000000..f00e215
--- /dev/null
+++ b/doc/device-tree-bindings/serial/microchip,pic32-uart.txt
@@ -0,0 +1,5 @@
+* Microchip PIC32 serial UART
+
+Required properties:
+- compatible: must be "microchip,pic32mzda-uart".
+- reg: exactly one register range.
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 1fc287e..9763ea1 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -107,6 +107,14 @@ config DEBUG_UART_APBUART
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_PIC32
+ bool "Microchip PIC32"
+ help
+ Select this to enable a debug UART using the serial_pic32 driver. You
+ will need to provide parameters to make this work. The driver will
+ be available until the real driver model serial is running.
+
+
endchoice

config DEBUG_UART_BASE
@@ -223,4 +231,9 @@ config UNIPHIER_SERIAL
If you have a UniPhier based board and want to use the on-chip
serial ports, say Y to this option. If unsure, say N.

+config PIC32_SERIAL
+ bool "Support for Microchip PIC32 on-chip UART"
+ help
+ Support for the UART found on Microchip PIC32 SoC's.
+
endmenu
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index dd87147..57cd38b 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_MXS_AUART) += mxs_auart.o
obj-$(CONFIG_ARC_SERIAL) += serial_arc.o
obj-$(CONFIG_UNIPHIER_SERIAL) += serial_uniphier.o
obj-$(CONFIG_STM32_SERIAL) += serial_stm32.o
+obj-$(CONFIG_PIC32_SERIAL) += serial_pic32.o

ifndef CONFIG_SPL_BUILD
obj-$(CONFIG_USB_TTY) += usbtty.o
diff --git a/drivers/serial/serial_pic32.c b/drivers/serial/serial_pic32.c
new file mode 100644
index 0000000..ee9d056
--- /dev/null
+++ b/drivers/serial/serial_pic32.c
@@ -0,0 +1,199 @@
+/*
+ * (c) 2015 Paul Thacker <paul.thacker@microchip.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ */
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <serial.h>
+#include <wait_bit.h>
+#include <mach/pic32.h>
+#include <dt-bindings/clock/microchip,clock.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* UART Control Registers */
+#define U_MOD 0x00
+#define U_MODCLR (U_MOD + _CLR_OFFSET)
+#define U_MODSET (U_MOD + _SET_OFFSET)
+#define U_STA 0x10
+#define U_STACLR (U_STA + _CLR_OFFSET)
+#define U_STASET (U_STA + _SET_OFFSET)
+#define U_TXR 0x20
+#define U_RXR 0x30
+#define U_BRG 0x40
+
+/* U_MOD bits */
+#define UART_ENABLE BIT(15)
+
+/* U_STA bits */
+#define UART_RX_ENABLE BIT(12)
+#define UART_TX_BRK BIT(11)
+#define UART_TX_ENABLE BIT(10)
+#define UART_TX_FULL BIT(9)
+#define UART_TX_EMPTY BIT(8)
+#define UART_RX_OERR BIT(1)
+#define UART_RX_DATA_AVAIL BIT(0)
+
+struct pic32_uart_priv {
+ void __iomem *base;
+ ulong uartclk;
+};
+
+/*
+ * Initialize the serial port with the given baudrate.
+ * The settings are always 8 data bits, no parity, 1 stop bit, no start bits.
+ */
+static int pic32_serial_init(void __iomem *base, ulong clk, u32 baudrate)
+{
+ u32 div = DIV_ROUND_CLOSEST(clk, baudrate * 16);
+
+ /* wait for TX FIFO to empty */
+ wait_for_bit(__func__, base + U_STA, UART_TX_EMPTY,
+ true, CONFIG_SYS_HZ, false);
+
+ /* send break */
+ writel(UART_TX_BRK, base + U_STASET);
+
+ /* disable and clear mode */
+ writel(0, base + U_MOD);
+ writel(0, base + U_STA);
+
+ /* set baud rate generator */
+ writel(div - 1, base + U_BRG);
+
+ /* enable the UART for TX and RX */
+ writel(UART_TX_ENABLE | UART_RX_ENABLE, base + U_STASET);
+
+ /* enable the UART */
+ writel(UART_ENABLE, base + U_MODSET);
+ return 0;
+}
+
+/* Check number of characters ready in RX Fifo */
+static int pic32_uart_pending_input(void __iomem *base)
+{
+ /* check if rx buffer overrun error has occurred */
+ if (readl(base + U_STA) & UART_RX_OERR) {
+ readl(base + U_RXR);
+
+ /* clear OERR to keep receiving */
+ writel(UART_RX_OERR, base + U_STACLR);
+ }
+
+ return readl(base + U_STA) & UART_RX_DATA_AVAIL;
+}
+
+static int pic32_uart_pending(struct udevice *dev, bool input)
+{
+ struct pic32_uart_priv *priv = dev_get_priv(dev);
+
+ if (input)
+ return pic32_uart_pending_input(priv->base);
+
+ return !(readl(priv->base + U_STA) & UART_TX_EMPTY);
+}
+
+static int pic32_uart_setbrg(struct udevice *dev, int baudrate)
+{
+ struct pic32_uart_priv *priv = dev_get_priv(dev);
+
+ return pic32_serial_init(priv->base, priv->uartclk, baudrate);
+}
+
+static int pic32_uart_putc(struct udevice *dev, const char ch)
+{
+ struct pic32_uart_priv *priv = dev_get_priv(dev);
+
+ /* Check if Tx FIFO is full */
+ if (readl(priv->base + U_STA) & UART_TX_FULL)
+ return -EAGAIN;
+
+ /* pump the char to tx buffer */
+ writel(ch, priv->base + U_TXR);
+
+ return 0;
+}
+
+static int pic32_uart_getc(struct udevice *dev)
+{
+ struct pic32_uart_priv *priv = dev_get_priv(dev);
+
+ /* return error if RX fifo is empty */
+ if (!pic32_uart_pending_input(priv->base))
+ return -EAGAIN;
+
+ /* read the character from rx buffer */
+ return readl(priv->base + U_RXR) & 0xff;
+}
+
+static int pic32_uart_probe(struct udevice *dev)
+{
+ struct pic32_uart_priv *priv = dev_get_priv(dev);
+ struct udevice *clkdev;
+ fdt_addr_t addr;
+ fdt_size_t size;
+ int ret;
+
+ /* get address */
+ addr = fdtdec_get_addr_size(gd->fdt_blob, dev->of_offset, "reg", &size);
+ if (addr == FDT_ADDR_T_NONE)
+ return -EINVAL;
+
+ priv->base = ioremap(addr, size);
+ if (!priv->base)
+ return -EINVAL;
+
+ /* get clock rate */
+ ret = uclass_get_device(UCLASS_CLK, 0, &clkdev);
+ if (ret) {
+ printf("clk class not found, %d\n", ret);
+ return ret;
+ }
+ priv->uartclk = clk_get_periph_rate(clkdev, PB2CLK);
+
+ /* initialize serial */
+ return pic32_serial_init(priv->base, priv->uartclk, CONFIG_BAUDRATE);
+}
+
+static const struct dm_serial_ops pic32_uart_ops = {
+ .putc = pic32_uart_putc,
+ .pending = pic32_uart_pending,
+ .getc = pic32_uart_getc,
+ .setbrg = pic32_uart_setbrg,
+};
+
+static const struct udevice_id pic32_uart_ids[] = {
+ { .compatible = "microchip,pic32mzda-uart" },
+ {}
+};
+
+U_BOOT_DRIVER(pic32_serial) = {
+ .name = "pic32-uart",
+ .id = UCLASS_SERIAL,
+ .of_match = pic32_uart_ids,
+ .probe = pic32_uart_probe,
+ .ops = &pic32_uart_ops,
+ .flags = DM_FLAG_PRE_RELOC,
+ .priv_auto_alloc_size = sizeof(struct pic32_uart_priv),
+};
+
+#ifdef CONFIG_DEBUG_UART_PIC32
+#include <debug_uart.h>
+
+static inline void _debug_uart_init(void)
+{
+ void __iomem *base = (void __iomem *)CONFIG_DEBUG_UART_BASE;
+
+ pic32_serial_init(base, CONFIG_DEBUG_UART_CLOCK, CONFIG_BAUDRATE);
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+ writel(ch, CONFIG_DEBUG_UART_BASE + U_TXR);
+}
+
+DEBUG_UART_FUNCS
+#endif
--
1.8.3.1