[U-Boot] [PATCH v3 06/14] drivers: serial: add driver for Microchip PIC32 UART controller.
Simon Glass
sjg at chromium.org
Wed Jan 13 21:09:40 CET 2016
Hi Purna,
On 12 January 2016 at 03:18, Purna Chandra Mandal
<purna.mandal at microchip.com> wrote:
>
> From: Paul Thacker <paul.thacker at microchip.com>
>
> This adds PIC32 UART controller support based on driver model.
>
> Signed-off-by: Paul Thacker <paul.thacker at microchip.com>
> Signed-off-by: Purna Chandra Mandal <purna.mandal at microchip.com>
>
>
> ---
>
> 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
>
Reviewed-by: Simon Glass <sjg at chromium.org>
One nit/question below.
> 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 at 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 */
But what does it return? The number of available characters? Please
make the comment more specific.
> +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);
Should return the number of characters available. Should this be?
return pic32_uart_pending_input(priv->base) ? 1 : 0;
Of course I don't quite know what pic32_uart_pending_input() does, so
I could be wrong.
> +
> + 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;
> +
> + /* 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
> --
> 1.8.3.1
>
Regards,
Simon
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