[PATCH 13/20] i.MX: Add 'lpuart' serial driver
Sascha Hauer
s.hauer at pengutronix.de
Tue Oct 4 00:13:14 PDT 2016
On Mon, Oct 03, 2016 at 07:40:50AM -0700, Andrey Smirnov wrote:
> Add 'lpuart' serial driver, based on analogous driver from U-Boot
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov at gmail.com>
> ---
> drivers/serial/Kconfig | 4 +
> drivers/serial/Makefile | 1 +
> drivers/serial/serial_lpuart.c | 217 +++++++++++++++++++++++++++++++++++++++++
> include/serial/lpuart.h | 28 ++++--
> 4 files changed, 244 insertions(+), 6 deletions(-)
> create mode 100644 drivers/serial/serial_lpuart.c
>
> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> index 146bf1e..02e869a 100644
> --- a/drivers/serial/Kconfig
> +++ b/drivers/serial/Kconfig
> @@ -137,4 +137,8 @@ config DRIVER_SERIAL_DIGIC
> bool "Canon DIGIC serial driver"
> depends on ARCH_DIGIC
>
> +config DRIVER_SERIAL_LPUART
> + depends on ARCH_IMX
> + bool "LPUART serial driver"
> +
> endmenu
> diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
> index 189e777..7d1bae1 100644
> --- a/drivers/serial/Makefile
> +++ b/drivers/serial/Makefile
> @@ -20,3 +20,4 @@ obj-$(CONFIG_DRIVER_SERIAL_AUART) += serial_auart.o
> obj-$(CONFIG_DRIVER_SERIAL_CADENCE) += serial_cadence.o
> obj-$(CONFIG_DRIVER_SERIAL_EFI_STDIO) += efi-stdio.o
> obj-$(CONFIG_DRIVER_SERIAL_DIGIC) += serial_digic.o
> +obj-$(CONFIG_DRIVER_SERIAL_LPUART) += serial_lpuart.o
> diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
> new file mode 100644
> index 0000000..52fb6d3
> --- /dev/null
> +++ b/drivers/serial/serial_lpuart.c
> @@ -0,0 +1,217 @@
> +/*
> + * Copyright (c) 2016 Zodiac Inflight Innovation
> + * Author: Andrey Smirnov <andrew.smirnov at gmail.com>
> + *
> + * Based on analogous driver from U-Boot
> + *
> + * See file CREDITS for list of people who contributed to this
> + * project.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <common.h>
> +#include <driver.h>
> +#include <init.h>
> +#include <malloc.h>
> +#include <notifier.h>
> +#include <io.h>
> +#include <of.h>
> +#include <linux/err.h>
> +#include <linux/clk.h>
> +#include <serial/lpuart.h>
> +
> +struct lpuart {
> + struct console_device cdev;
> + int baudrate;
> + int dte_mode;
> + struct notifier_block notify;
> + struct resource *io;
> + void __iomem *base;
> + struct clk *clk;
> +};
> +
> +static struct lpuart *cdev_to_lpuart(struct console_device *cdev)
> +{
> + return container_of(cdev, struct lpuart, cdev);
> +}
> +
> +static struct lpuart *nb_to_lpuart(struct notifier_block *nb)
> +{
> + return container_of(nb, struct lpuart, notify);
> +}
> +
> +static void lpuart_enable(struct lpuart *lpuart, bool on)
> +{
> + u8 ctrl;
> +
> + ctrl = readb(lpuart->base + UARTCR2);
> + if (on)
> + ctrl |= UARTCR2_TE | UARTCR2_RE;
> + else
> + ctrl &= ~(UARTCR2_TE | UARTCR2_RE);
> + writeb(ctrl, lpuart->base + UARTCR2);
> +}
> +
> +static int lpuart_serial_setbaudrate(struct console_device *cdev,
> + int baudrate)
> +{
> + struct lpuart *lpuart = cdev_to_lpuart(cdev);
> +
> + lpuart_enable(lpuart, false);
> +
> + lpuart_setbrg(lpuart->base,
> + clk_get_rate(lpuart->clk),
> + baudrate);
> +
> + lpuart_enable(lpuart, true);
> +
> + lpuart->baudrate = baudrate;
> +
> + return 0;
> +}
> +
> +static int lpuart_serial_getc(struct console_device *cdev)
> +{
> + bool ready;
> + struct lpuart *lpuart = cdev_to_lpuart(cdev);
> +
> + do {
> + const u8 sr1 = readb(lpuart->base + UARTSR1);
> + ready = !!(sr1 & (UARTSR1_OR | UARTSR1_RDRF));
> + } while (!ready);
> +
> + return readb(lpuart->base + UARTDR);
> +}
> +
> +static void lpuart_serial_putc(struct console_device *cdev, char c)
> +{
> + lpuart_putc(cdev_to_lpuart(cdev)->base, c);
> +}
> +
> +/* Test whether a character is in the RX buffer */
> +static int lpuart_serial_tstc(struct console_device *cdev)
> +{
> + return !!readb(cdev_to_lpuart(cdev)->base + UARTRCFIFO);
> +}
> +
> +static void lpuart_serial_flush(struct console_device *cdev)
> +{
> + bool tx_empty;
> + struct lpuart *lpuart = cdev_to_lpuart(cdev);
> +
> + do {
> + const u8 sr1 = readb(lpuart->base + UARTSR1);
> + tx_empty = !!(sr1 & UARTSR1_TDRE);
> + } while (!tx_empty);
> +}
> +
> +static int lpuart_clocksource_clock_change(struct notifier_block *nb,
> + unsigned long event, void *data)
> +{
> + struct lpuart *lpuart = nb_to_lpuart(nb);
> +
> + return lpuart_serial_setbaudrate(&lpuart->cdev, lpuart->baudrate);
> +}
This doesn't make sense in this form. I introduced this code in the i.MX
uart driver since I had the need to change PLL rates while the uart is
active. When this happens I had to adjust the dividers for the new uart
base clock. The code above doesn't react to base clock changes though,
it takes the old rate stored in lpuart->baudrate.
If you don't have to adjust PLL rates while the uart is active then I
suggest that you just remove this code.
> @@ -225,25 +225,35 @@ static inline void lpuart_setbrg(void __iomem *base,
> unsigned int refclock,
> unsigned int baudrate)
> {
> + unsigned int bfra;
> u16 sbr;
> +
> sbr = (u16) (refclock / (16 * baudrate));
>
> writeb(sbr >> 8, base + UARTBDH);
> writeb(sbr & 0xff, base + UARTBDL);
> +
> + bfra = DIV_ROUND_UP(2 * refclock, baudrate) - 32 * sbr;
> + bfra &= UARTCR4_BRFA_MASK;
> + writeb(bfra, base + UARTCR4);
> }
>
> -static inline void lpuart_setup(void __iomem *base,
> - unsigned int refclock)
> +static inline void lpuart_setup_with_fifo(void __iomem *base,
> + unsigned int refclock,
> + unsigned int twfifo)
> {
> -
> /* Disable UART */
> writeb(0, base + UARTCR2);
> writeb(0, base + UARTMODEM);
> writeb(0, base + UARTCR1);
>
> - /* Disable FIFOs */
> - writeb(0, base + UARTPFIFO);
> - writeb(0, base + UARTTWFIFO);
> + if (twfifo) {
> + writeb(UARTPFIFO_TXFE | UARTPFIFO_RXFE, base + UARTPFIFO);
> + writeb((u8)twfifo, base + UARTTWFIFO);
> + } else {
> + writeb(0, base + UARTPFIFO);
> + writeb(0, base + UARTTWFIFO);
> + }
> writeb(1, base + UARTRWFIFO);
> writeb(UARTCFIFO_RXFLUSH | UARTCFIFO_TXFLUSH, base + UARTCFIFO);
>
> @@ -252,6 +262,12 @@ static inline void lpuart_setup(void __iomem *base,
> writeb(UARTCR2_TE | UARTCR2_RE, base + UARTCR2);
> }
>
> +static inline void lpuart_setup(void __iomem *base,
> + unsigned int refclock)
> +{
> + lpuart_setup_with_fifo(base, refclock, 0x00);
> +}
> +
> static inline void lpuart_putc(void __iomem *base, int c)
> {
> if (!(readb(base + UARTCR2) & UARTCR2_TE))
This was introduced earlier with this series. No need to change it, just
create it correctly in the first place.
Sascha
--
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