--- /dev/null
+/*
+ * (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_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
projects / u-boot.git / commitdiff
