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

[Purna Chandra Mandal <purna.mandal@microchip.com>]

On 01/13/2016 07:33 PM, Daniel Schwierzeck wrote:

> Am Mittwoch, den 13.01.2016, 14:49 +0100 schrieb Daniel Schwierzeck:
>> 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
> I forgot one thing
>>> ---
>>>
>>> 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"
> you should add
>
> depends on DM_SERIAL && MACH_PIC32

ack. Will add.

>>> +	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.

ack.

>>> +
>>> +	/* 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