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

Purna Chandra Mandal
2016-01-14T05:42:19Z

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