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

This adds PIC32 UART controller support based on driver model.

Signed-off-by: Paul Thacker <paul.thac...@microchip.com>
Signed-off-by: Purna Chandra Mandal <purna.man...@microchip.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierz...@gmail.com>
Reviewed-by: Tom Rini <tr...@konsulko.com>
Reviewed-by: Simon Glass <s...@chromium.org>


---

Changes in v4:
- update kconfig dependency (DM_SERIAL && MACH_PIC32)
- update comment for _pending_input().
- rename UART_RX_OERR to UART_RX_OVER.
- DEBUG_UART_PIC32 now depends on PIC32_SERIAL
- extract clk_id from device-tree

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                             |  15 ++
 drivers/serial/Makefile                            |   1 +
 drivers/serial/serial_pic32.c                      | 198 +++++++++++++++++++++
 4 files changed, 219 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 83068cf..43b2ec3 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -143,6 +143,14 @@ config DEBUG_UART_PL011
          work. The driver will be available until the real driver model
          serial is running.
 
+config DEBUG_UART_PIC32
+       bool "Microchip PIC32"
+       depends on PIC32_SERIAL
+       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
@@ -234,6 +242,13 @@ config FSL_LPUART
          Select this to enable a Low Power UART for Freescale VF610 and
          QorIQ Layerscape devices.
 
+config PIC32_SERIAL
+       bool "Support for Microchip PIC32 on-chip UART"
+       depends on DM_SERIAL && MACH_PIC32
+       default y
+       help
+         Support for the UART found on Microchip PIC32 SoC's.
+
 config SYS_NS16550
        bool "NS16550 UART or compatible"
        help
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..af9fbbf
--- /dev/null
+++ b/drivers/serial/serial_pic32.c
@@ -0,0 +1,198 @@
+/*
+ * (c) 2015 Paul Thacker <paul.thac...@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_OVER           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 whether any char pending 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_OVER) {
+               readl(base + U_RXR);
+
+               /* clear overrun error to keep receiving */
+               writel(UART_RX_OVER, base + U_STACLR);
+       }
+
+       /* In PIC32 there is no way to know number of outstanding
+        * chars in rx-fifo. Only it can be known whether there is any.
+        */
+       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);
+
+       /* get clock rate */
+       ret = clk_get_by_index(dev, 0, &clkdev);
+       if (ret < 0)
+               return ret;
+       priv->uartclk = clk_get_periph_rate(clkdev, ret);
+
+       /* 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

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