[U-Boot] [PATCH v3 06/14] drivers: serial: add driver for Microchip PIC32 UART controller.

[Daniel Schwierzeck <daniel.schwierzeck@gmail.com>]

Am Dienstag, den 12.01.2016, 15:48 +0530 schrieb Purna Chandra Mandal:
> From: Paul Thacker <paul.thacker@microchip.com>
> 
> This adds PIC32 UART controller support based on driver model.
> 
> Signed-off-by: Paul Thacker <paul.thacker@microchip.com>
> Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
> 

Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

nits below

> 
> ---
> 
> 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                             |  13 ++
>  drivers/serial/Makefile                            |   1 +
>  drivers/serial/serial_pic32.c                      | 199
> +++++++++++++++++++++
>  4 files changed, 218 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..ee9d056
> --- /dev/null
> +++ b/drivers/serial/serial_pic32.c
> @@ -0,0 +1,199 @@
> +/*
> + * (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_OERR		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 number of characters ready 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_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;
> +}
> +
> +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);
> +	if (!priv->base)
> +		return -EINVAL;

you can drop this check. ioremap() always returns a mapped address.

> +
> +	/* 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);
> +
> +	/* 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
-- 
- Daniel