[U-Boot] [PATCH v1 05/18] drivers: serial: add driver for Microchip PIC32 UART controller.

[Purna Chandra Mandal <purna.mandal@microchip.com>]

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

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

 drivers/serial/Kconfig        |  13 +++
 drivers/serial/Makefile       |   1 +
 drivers/serial/serial_pic32.c | 220 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 234 insertions(+)
 create mode 100644 drivers/serial/serial_pic32.c

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..01c62e7
--- /dev/null
+++ b/drivers/serial/serial_pic32.c
@@ -0,0 +1,220 @@
+/*
+ * (c) 2015 Paul Thacker <paul.thacker@microchip.com>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ *
+ */
+#include <common.h>
+#include <dm.h>
+#include <clk.h>
+#include <errno.h>
+#include <config.h>
+#include <serial.h>
+#include <linux/bitops.h>
+#include <common.h>
+#include <asm/io.h>
+#include <asm/arch-pic32/pic32.h>
+#include <asm/arch-pic32/clock.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define UART_ENABLE        BIT(15)
+#define UART_ENABLE_RX        BIT(12)
+#define UART_ENABLE_TX        BIT(10)
+#define UART_RX_DATA_AVAIL    BIT(0)
+#define UART_RX_OERR        BIT(1)
+#define UART_TX_FULL        BIT(9)
+
+/* UART Control */
+#define U_BASE(x)    (x)
+#define U_MODE(x)       U_BASE(x)
+#define U_MODECLR(x)    (U_MODE(x) + _CLR_OFFSET)
+#define U_MODESET(x)    (U_MODE(x) + _SET_OFFSET)
+#define U_STA(x)        (U_BASE(x) + 0x10)
+#define U_STACLR(x)     (U_STA(x) + _CLR_OFFSET)
+#define U_STASET(x)     (U_STA(x) + _SET_OFFSET)
+#define U_TXREG(x)      (U_BASE(x) + 0x20)
+#define U_RXREG(x)      (U_BASE(x) + 0x30)
+#define U_BRG(x)        (U_BASE(x) + 0x40)
+
+struct pic32_uart_priv {
+    void __iomem *regs;
+    ulong uartclk;
+};
+
+static void pic32_serial_setbrg(void __iomem *regs, ulong uart_clk, u32 baud)
+{
+    writel(0, U_BRG(regs));
+    writel((uart_clk / baud / 16) - 1, U_BRG(regs));
+    udelay(100);
+}
+
+/*
+ * 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 *regs, ulong clk, u32 baudrate)
+{
+    /* disable and clear mode */
+    writel(0, U_MODE(regs));
+    writel(0, U_STA(regs));
+
+    /* set baud rate generator */
+    pic32_serial_setbrg(regs, clk, baudrate);
+
+    /* enable the UART for TX and RX */
+    writel(UART_ENABLE_TX | UART_ENABLE_RX, U_STASET(regs));
+
+    /* enable the UART */
+    writel(UART_ENABLE, U_MODESET(regs));
+    return 0;
+}
+
+/* Output a single byte to the serial port */
+static void pic32_serial_putc(void __iomem *regs, const char c)
+{
+    /* if \n, then add a \r */
+    if (c == '\n')
+        pic32_serial_putc(regs, '\r');
+
+    /* Wait for Tx FIFO not full */
+    while (readl(U_STA(regs)) & UART_TX_FULL)
+        ;
+
+    /* stuff the tx buffer with the character */
+    writel(c, U_TXREG(regs));
+}
+
+/* Test whether a character is in the RX buffer */
+static int pic32_serial_tstc(void __iomem *regs)
+{
+    /* check if rcv buf overrun error has occurred */
+    if (readl(U_STA(regs)) & UART_RX_OERR) {
+        readl(U_RXREG(regs));
+
+        /* clear OERR to keep receiving */
+        writel(UART_RX_OERR, U_STACLR(regs));
+    }
+
+    if (readl(U_STA(regs)) & UART_RX_DATA_AVAIL)
+        return 1;    /* yes, there is data in rcv buffer */
+    else
+        return 0;    /* no data in rcv buffer */
+}
+
+/*
+ * Read a single byte from the rx buffer.
+ * Blocking: waits until a character is received, then returns.
+ * Return the character read directly from the UART's receive register.
+ *
+ */
+static int pic32_serial_getc(void __iomem *regs)
+{
+    /* wait here until data is available */
+    while (!pic32_serial_tstc(regs))
+        ;
+
+    /* read the character from the rcv buffer */
+    return readl(U_RXREG(regs));
+}
+
+static int pic32_uart_pending(struct udevice *dev, bool input)
+{
+    struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+    return pic32_serial_tstc(priv->regs);
+}
+
+static int pic32_uart_setbrg(struct udevice *dev, int baudrate)
+{
+    struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+    pic32_serial_init(priv->regs, priv->uartclk, baudrate);
+    return 0;
+}
+
+static int pic32_uart_putc(struct udevice *dev, const char ch)
+{
+    struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+    pic32_serial_putc(priv->regs, ch);
+    return 0;
+}
+
+static int pic32_uart_getc(struct udevice *dev)
+{
+    struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+    return pic32_serial_getc(priv->regs);
+}
+
+static int pic32_uart_probe(struct udevice *dev)
+{
+    struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+    pic32_serial_init(priv->regs, priv->uartclk, CONFIG_BAUDRATE);
+    return 0;
+}
+
+static int pic32_uart_ofdata_to_platdata(struct udevice *dev)
+{
+    struct pic32_uart_priv *priv = dev_get_platdata(dev);
+    struct udevice *clkdev;
+    int ret;
+
+    priv->regs = map_physmem(dev_get_addr(dev),
+                 0x100,
+                 MAP_NOCACHE);
+
+    /* 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);
+
+    return 0;
+}
+
+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,
+    .ofdata_to_platdata = pic32_uart_ofdata_to_platdata,
+    .platdata_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 *regs = (void __iomem *)CONFIG_DEBUG_UART_BASE;
+
+    pic32_serial_init(regs, CONFIG_DEBUG_UART_CLOCK, CONFIG_BAUDRATE);
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+    writel(ch, U_TXREG(CONFIG_DEBUG_UART_BASE));
+}
+
+DEBUG_UART_FUNCS
+
+#endif
-- 
1.8.3.1