drivers: serial: add driver for Microchip PIC32 UART controller.

Signed-off-by Paul Thacker <[email protected]>

Signed-off-by Purna Chandra Mandal <[email protected]>

---

Changes in v2:
- fix missing or corrupted chars during baud rate change
- remove loop until any new char is available in _getc()

 .../serial/microchip,pic32-uart.txt                |   5 +
 drivers/serial/Kconfig                             |  13 ++
 drivers/serial/Makefile                            |   1 +
 drivers/serial/serial_pic32.c                      | 230 +++++++++++++++++++++
 4 files changed, 249 insertions(+)
 create mode 100644 doc/device-tree-bindings/serial/microchip,pic32-uart.txt
 create mode 100644 drivers/serial/serial_pic32.c

doc/device-tree-bindings/serial/microchip,pic32-uart.txt new file +5 -0

new file mode 100644
index 0000000..f00e215
@@ -0,0 +1,5 @@
+* Microchip PIC32 serial UART
+
+Required properties:
+- compatible: must be "microchip,pic32mzda-uart".
+- reg: exactly one register range.

drivers/serial/Kconfig +13 -0

index 1fc287e..9763ea1 100644
@@ -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

drivers/serial/Makefile +1 -0

index dd87147..57cd38b 100644
@@ -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

drivers/serial/serial_pic32.c new file +75 -0

new file mode 100644
index 0000000..3eddb57
@@ -0,0 +1,230 @@
+/*
+ * (c) 2015 Paul Thacker <[email protected]>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ *
+ */
+#include <common.h>
+#include <config.h>
+#include <dm.h>
+#include <clk.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;
+};
+
+static void pic32_serial_setbrg(void __iomem *base, ulong uart_clk, u32 baud)
+{
+       writel(0, base + U_BRG);
+       writel((uart_clk / baud / 16) - 1, base + U_BRG);
+}
+
+/*
+ * 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)
+{
+       /* 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 */
+       pic32_serial_setbrg(base, clk, baudrate);
+
+       /* enable the UART for TX and RX */
+       writel(UART_TX_ENABLE | UART_RX_ENABLE, base + U_STASET);
+
+       /* enable the UART */

drivers/serial/serial_pic32.c new file +87 -0

+
+       /* stuff the tx buffer with the character */
+       writel(c, base + U_TXR);
+}
+
+/* Check number of characters in RX fifo */
+static int pic32_serial_tstc(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;
+}
+
+/*
+ * Read a single byte from rx fifo.
+ * 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 *base)
+{
+       /* return error until data is available */
+       if (!pic32_serial_tstc(base))
+               return -EAGAIN;
+
+       /* read the character from rx buffer */
+       return readl(base + U_RXR) & 0xff;
+}
+
+static int pic32_uart_pending(struct udevice *dev, bool input)
+{
+       struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+       if (input)
+               return pic32_serial_tstc(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_platdata(dev);
+
+       pic32_serial_init(priv->base, 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->base, 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->base);
+}
+
+static int pic32_uart_probe(struct udevice *dev)
+{
+       struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+       pic32_serial_init(priv->base, 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;
+       fdt_addr_t addr;
+       int ret;
+
+       /* get address */
+       addr = dev_get_addr(dev);
+       if (addr == FDT_ADDR_T_NONE)
+               return -EINVAL;
+

drivers/serial/serial_pic32.c new file +15 -0

+
+       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" },
+       {}
+};

drivers/serial/serial_pic32.c new file +19 -1

+};
+
+#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

2016-01-04 15:00 GMT+01:00 Purna Chandra Mandal <[email protected]>:

Quoted 153 lines

Signed-off-by Paul Thacker <[email protected]>

Signed-off-by Purna Chandra Mandal <[email protected]>

---

Changes in v2:
- fix missing or corrupted chars during baud rate change
- remove loop until any new char is available in _getc()

 .../serial/microchip,pic32-uart.txt                |   5 +
 drivers/serial/Kconfig                             |  13 ++
 drivers/serial/Makefile                            |   1 +
 drivers/serial/serial_pic32.c                      | 230 +++++++++++++++++++++
 4 files changed, 249 insertions(+)
 create mode 100644 doc/device-tree-bindings/serial/microchip,pic32-uart.txt
 create mode 100644 drivers/serial/serial_pic32.c

doc/device-tree-bindings/serial/microchip,pic32-uart.txt new file +5 -0

new file mode 100644
index 0000000..f00e215
@@ -0,0 +1,5 @@
+* Microchip PIC32 serial UART
+
+Required properties:
+- compatible: must be "microchip,pic32mzda-uart".
+- reg: exactly one register range.

drivers/serial/Kconfig +13 -0

index 1fc287e..9763ea1 100644
@@ -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

drivers/serial/Makefile +1 -0

index dd87147..57cd38b 100644
@@ -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

drivers/serial/serial_pic32.c new file +78 -0

new file mode 100644
index 0000000..3eddb57
@@ -0,0 +1,230 @@
+/*
+ * (c) 2015 Paul Thacker <[email protected]>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ *
+ */
+#include <common.h>
+#include <config.h>
+#include <dm.h>
+#include <clk.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;
+};
+
+static void pic32_serial_setbrg(void __iomem *base, ulong uart_clk, u32 baud)
+{
+       writel(0, base + U_BRG);
+       writel((uart_clk / baud / 16) - 1, base + U_BRG);
+}
+
+/*
+ * 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)
+{
+       /* 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 */
+       pic32_serial_setbrg(base, clk, baudrate);
+
+       /* 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;
+}

drivers/serial/serial_pic32.c line 85

Quoted 7 lines

drivers/serial/serial_pic32.c new file +7 -0

+
+/* Output a single byte to the serial port */
+static void pic32_serial_putc(void __iomem *base, const char c)
+{
+       /* if \n, then add a \r */
+       if (c == '\n')
+               pic32_serial_putc(base, '\r');

you can drop this because the serial uclass code takes care of it

drivers/serial/serial_pic32.c line 89

Quoted 4 lines

drivers/serial/serial_pic32.c new file +4 -0

+
+       /* Wait for Tx FIFO not full */
+       wait_for_bit(__func__, base + U_STA, UART_TX_FULL,
+                    false, CONFIG_SYS_HZ, false);

you should merge this function with pic32_uart_putc(). Then remove the wait loop and only return -EAGAIN if there is no space in the TX FIFO .

Quoted 91 lines

drivers/serial/serial_pic32.c new file +91 -0

+
+       /* stuff the tx buffer with the character */
+       writel(c, base + U_TXR);
+}
+
+/* Check number of characters in RX fifo */
+static int pic32_serial_tstc(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;
+}
+
+/*
+ * Read a single byte from rx fifo.
+ * 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 *base)
+{
+       /* return error until data is available */
+       if (!pic32_serial_tstc(base))
+               return -EAGAIN;
+
+       /* read the character from rx buffer */
+       return readl(base + U_RXR) & 0xff;
+}
+
+static int pic32_uart_pending(struct udevice *dev, bool input)
+{
+       struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+       if (input)
+               return pic32_serial_tstc(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_platdata(dev);
+
+       pic32_serial_init(priv->base, 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->base, 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->base);
+}
+
+static int pic32_uart_probe(struct udevice *dev)
+{
+       struct pic32_uart_priv *priv = dev_get_platdata(dev);
+
+       pic32_serial_init(priv->base, 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;
+       fdt_addr_t addr;
+       int ret;
+
+       /* get address */
+       addr = dev_get_addr(dev);
+       if (addr == FDT_ADDR_T_NONE)
+               return -EINVAL;
+
+       priv->base = pic32_ioremap(addr);
+
+       /* get clock rate */
+       ret = uclass_get_device(UCLASS_CLK, 0, &clkdev);

drivers/serial/serial_pic32.c line 186

Quoted 6 lines

drivers/serial/serial_pic32.c new file +6 -0

+       if (ret) {
+               printf("clk class not found, %d\n", ret);
+               return ret;
+       }
+
+       priv->uartclk = clk_get_periph_rate(clkdev, PB2CLK);

all that code could be done in pic32_uart_probe(). you do not need to implement ofdata_to_platdata in DT-only drivers

Quoted 18 lines

drivers/serial/serial_pic32.c new file +18 -0

+
+       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",

drivers/serial/serial_pic32.c line 211

Quoted 7 lines

drivers/serial/serial_pic32.c new file +7 -0

+       .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),

allocation of driver private data should be requested with priv_auto_alloc_size

Quoted 22 lines

drivers/serial/serial_pic32.c new file +19 -1

+};
+
+#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