[U-Boot] [PATCH v2 04/13] drivers: serial: add driver for Microchip PIC32 UART controller.

Daniel Schwierzeck daniel.schwierzeck at gmail.com
Tue Jan 5 20:59:09 CET 2016


2016-01-04 15:00 GMT+01:00 Purna Chandra Mandal <purna.mandal at microchip.com>:
> Signed-off-by: Paul Thacker <paul.thacker at microchip.com>
> Signed-off-by: Purna Chandra Mandal <purna.mandal at microchip.com>
>
> ---
>
> 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
>
> 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..3eddb57
> --- /dev/null
> +++ b/drivers/serial/serial_pic32.c
> @@ -0,0 +1,230 @@
> +/*
> + * (c) 2015 Paul Thacker <paul.thacker at microchip.com>
> + *
> + * 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;
> +}
> +
> +/* 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

> +
> +       /* 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
.

> +
> +       /* 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);
> +       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

> +
> +       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),

allocation of driver private data should be requested with priv_auto_alloc_size

> +};
> +
> +#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
>
>



-- 
- Daniel


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