[U-Boot] [PATCH v1 01/16] serial: Add support for Qualcomm serial port

Simon Glass sjg at chromium.org
Mon Jan 11 17:57:40 CET 2016


Hi Mateusz,

On 6 January 2016 at 11:21, Mateusz Kulikowski
<mateusz.kulikowski at gmail.com> wrote:
> This driver works in "new" Data Mover UART mode, so
> will be compatible with modern Qualcomm chips only.
>
> Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski at gmail.com>
> ---
>
> Changes in v1:
> - Added (better) help to KConfig
> - Added dt binding documentation
> - Fixed include ordering
> - Reworked msm_serial_getc
> - Added error handling to msm_uart_clk_init (that is ignored later for now)
> - Dropped unneeded DM_FLAG_PRE_RELOC
>
>  doc/device-tree-bindings/serial/msm-serial.txt |   6 +
>  drivers/serial/Kconfig                         |   8 +
>  drivers/serial/Makefile                        |   1 +
>  drivers/serial/serial_msm.c                    | 206 +++++++++++++++++++++++++
>  4 files changed, 221 insertions(+)
>  create mode 100644 doc/device-tree-bindings/serial/msm-serial.txt
>  create mode 100644 drivers/serial/serial_msm.c

Reviewed-by: Simon Glass <sjg at chromium.org>

See note and a few nits below...

>
> diff --git a/doc/device-tree-bindings/serial/msm-serial.txt b/doc/device-tree-bindings/serial/msm-serial.txt
> new file mode 100644
> index 0000000..48b8428
> --- /dev/null
> +++ b/doc/device-tree-bindings/serial/msm-serial.txt
> @@ -0,0 +1,6 @@
> +Qualcomm UART (Data Mover mode)
> +
> +Required properties:
> +- compatible: must be "qcom,msm-uartdm-v1.4"
> +- reg: start address and size of the registers
> +- clock: interface clock (must accept baudrate as a frequency)
> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> index 1fc287e..56d7b76 100644
> --- a/drivers/serial/Kconfig
> +++ b/drivers/serial/Kconfig
> @@ -223,4 +223,12 @@ 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 MSM_SERIAL
> +       bool "Qualcomm on-chip UART"
> +       depends on DM_SERIAL
> +       help
> +         Support Data Mover UART used on Qualcomm Snapdragon SoCs.
> +         It should support all Qualcomm devices with UARTDM version 1.4,
> +         for example APQ8016 and MSM8916.
> +         Single baudrate is supported in current implementation (115200).
>  endmenu
> diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
> index dd87147..d052175 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-$(CONFIG_MSM_SERIAL) += serial_msm.o
>
>  ifndef CONFIG_SPL_BUILD
>  obj-$(CONFIG_USB_TTY) += usbtty.o
> diff --git a/drivers/serial/serial_msm.c b/drivers/serial/serial_msm.c
> new file mode 100644
> index 0000000..344f254
> --- /dev/null
> +++ b/drivers/serial/serial_msm.c
> @@ -0,0 +1,206 @@
> +/*
> + * Qualcomm UART driver
> + *
> + * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski at gmail.com>
> + *
> + * UART will work in Data Mover mode.
> + * Based on Linux driver.
> + *
> + * SPDX-License-Identifier:    GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <clk.h>
> +#include <dm.h>
> +#include <errno.h>
> +#include <serial.h>
> +#include <watchdog.h>
> +#include <asm/io.h>
> +#include <linux/compiler.h>
> +
> +/* Serial registers - this driver works in uartdm mode*/
> +
> +#define UARTDM_DMRX             0x34 /* Max RX transfer length */
> +#define UARTDM_NCF_TX           0x40 /* Number of chars to TX */
> +
> +#define UARTDM_RXFS             0x50 /* RX channel status register */
> +#define UARTDM_RXFS_BUF_SHIFT   0x7  /* Number of bytes in the packing buffer */
> +#define UARTDM_RXFS_BUF_MASK    0x7
> +
> +#define UARTDM_SR                0xA4 /* Status register */
> +#define UARTDM_SR_RX_READY       (1 << 0) /* Word is the receiver FIFO */
> +#define UARTDM_SR_TX_EMPTY       (1 << 3) /* Transmitter underrun */
> +#define UARTDM_SR_UART_OVERRUN   (1 << 4) /* Receive overrun */
> +
> +#define UARTDM_CR                         0xA8 /* Command register */
> +#define UARTDM_CR_CMD_RESET_ERR           (3 << 4) /* Clear overrun error */
> +#define UARTDM_CR_CMD_RESET_STALE_INT     (8 << 4) /* Clears stale irq */
> +#define UARTDM_CR_CMD_RESET_TX_READY      (3 << 8) /* Clears TX Ready irq*/
> +#define UARTDM_CR_CMD_FORCE_STALE         (4 << 8) /* Causes stale event */
> +#define UARTDM_CR_CMD_STALE_EVENT_DISABLE (6 << 8) /* Disable stale event */
> +
> +#define UARTDM_IMR                0xB0 /* Interrupt mask register */
> +#define UARTDM_ISR                0xB4 /* Interrupt status register */
> +#define UARTDM_ISR_TX_READY       0x80 /* TX FIFO empty */
> +
> +#define UARTDM_TF               0x100 /* UART Transmit FIFO register */
> +#define UARTDM_RF               0x140 /* UART Receive FIFO register */
> +
> +
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +struct msm_serial_data {
> +       phys_addr_t base;
> +       unsigned chars_cnt; /* number of buffered chars */
> +       uint32_t chars_buf; /* buffered chars */
> +};
> +
> +static int msm_serial_getc(struct udevice *dev)
> +{
> +       struct msm_serial_data *p = dev_get_priv(dev);
> +       char c;
> +       unsigned sr;
> +
> +       if (!p->chars_buf) {
> +               /* Clear error in case of buffer overrun */
> +               if (readl(p->base + UARTDM_SR) & UARTDM_SR_UART_OVERRUN)
> +                       writel(UARTDM_CR_CMD_RESET_ERR, p->base + UARTDM_CR);
> +
> +               /* We need to fetch new character */
> +               sr = readl(p->base + UARTDM_SR);
> +
> +               if (sr & UARTDM_SR_RX_READY) {
> +                       /* There are at least 4 bytes in fifo */
> +                       p->chars_buf = readl(p->base + UARTDM_RF);
> +                       p->chars_cnt = 4;
> +               } else {
> +                       /* Check if there is anything in fifo */
> +                       p->chars_cnt = readl(p->base + UARTDM_RXFS);
> +                       /* Extract number of characters in UART packing buffer*/
> +                       p->chars_cnt = (p->chars_cnt >> UARTDM_RXFS_BUF_SHIFT) &
> +                                      UARTDM_RXFS_BUF_MASK;
> +                       if (!p->chars_cnt)
> +                               return -EAGAIN;
> +
> +                       /* There is at least one charcter, move it to fifo */
> +                       writel(UARTDM_CR_CMD_FORCE_STALE, p->base + UARTDM_CR);
> +
> +                       p->chars_buf = readl(p->base + UARTDM_RF);
> +                       writel(UARTDM_CR_CMD_RESET_STALE_INT,
> +                              p->base + UARTDM_CR);
> +                       writel(0xFFFFFF, p->base + UARTDM_DMRX);
> +               }
> +       }
> +
> +       c = p->chars_buf & 0xFF;
> +       p->chars_buf >>= 8;
> +       p->chars_cnt--;
> +
> +       return c;
> +}
> +
> +static int msm_serial_putc(struct udevice *dev, const char ch)
> +{
> +       struct msm_serial_data *p = dev_get_priv(dev);
> +
> +       if (!(readl(p->base + UARTDM_SR) & UARTDM_SR_TX_EMPTY) &&
> +           !(readl(p->base + UARTDM_ISR) & UARTDM_ISR_TX_READY))
> +               return -EAGAIN;
> +
> +       writel(UARTDM_CR_CMD_RESET_TX_READY, p->base + UARTDM_CR);
> +
> +       writel(1, p->base + UARTDM_NCF_TX);
> +       writel(ch, p->base + UARTDM_TF);
> +       return 0;
> +}
> +
> +static int msm_serial_pending(struct udevice *dev, bool input)
> +{
> +       struct msm_serial_data *p = dev_get_priv(dev);
> +
> +       if (input) {
> +               if (p->chars_cnt)
> +                       return 1;
> +               if (readl(p->base + UARTDM_SR) & UARTDM_SR_RX_READY)
> +                       return 1;
> +               if (readl(p->base + UARTDM_RXFS))
> +                       return 1;
> +       }
> +       return 0;
> +}
> +
> +static const struct dm_serial_ops msm_serial_ops = {
> +       .putc = msm_serial_putc,
> +       .pending = msm_serial_pending,
> +       .getc = msm_serial_getc,
> +};
> +
> +static int msm_uart_clk_init(struct udevice *dev)
> +{
> +       uint clk_rate = fdtdec_get_uint(gd->fdt_blob, dev->of_offset,
> +                                       "clock-frequency", 115200);
> +       uint clkd[2]; /* clk_id and clk_no */
> +       int clk_offset;
> +       struct udevice *clk;
> +       int ret;
> +
> +       ret = fdtdec_get_int_array(gd->fdt_blob, dev->of_offset, "clock", clkd,
> +                                  2);
> +       if (ret)
> +               return ret;
> +
> +       clk_offset = fdt_node_offset_by_phandle(gd->fdt_blob, clkd[0]);
> +       if (clk_offset < 0)
> +               return clk_offset;
> +
> +       ret = uclass_get_device_by_of_offset(UCLASS_CLK, clk_offset, &clk);
> +       if (ret)
> +               return ret;

We can do much better than this in the future. Will have some patches
out soon. There is fdtdec_lookup_phandle() which helps a bit, but
really we want to get a clock directly. Anyway, this works for now.

> +
> +       ret = clk_set_periph_rate(clk, clkd[1], clk_rate);
> +       if (ret < 0)
> +               return ret;
> +
> +       return 0;
> +}
> +
> +static int msm_serial_probe(struct udevice *dev)
> +{
> +       struct msm_serial_data *p = dev_get_priv(dev);
> +
> +       msm_uart_clk_init(dev); /* Ignore return value and hope clock was
> +                                 properly initialized by earlier loaders */
> +
> +       if (readl(p->base + UARTDM_SR) & UARTDM_SR_UART_OVERRUN)
> +               writel(UARTDM_CR_CMD_RESET_ERR, p->base + UARTDM_CR);
> +
> +       writel(0, p->base + UARTDM_IMR);
> +       writel(UARTDM_CR_CMD_STALE_EVENT_DISABLE, p->base + UARTDM_CR);
> +       writel(0xFFFFFF, p->base + UARTDM_DMRX);

nit: please try to put a blank line before return.

> +       return 0;
> +}
> +
> +static int msm_serial_ofdata_to_platdata(struct udevice *dev)
> +{
> +       struct msm_serial_data *p = dev_get_priv(dev);

Please use *priv instead of *p. We should avoid single characters for
variable names.

> +
> +       p->base = dev_get_addr(dev);
> +       if (p->base == FDT_ADDR_T_NONE)
> +               return -EINVAL;
> +       return 0;
> +}
> +
> +static const struct udevice_id msm_serial_ids[] = {
> +       { .compatible = "qcom,msm-uartdm-v1.4" },
> +       { }
> +};
> +
> +U_BOOT_DRIVER(serial_msm) = {
> +       .name   = "serial_msm",
> +       .id     = UCLASS_SERIAL,
> +       .of_match = msm_serial_ids,
> +       .ofdata_to_platdata = ,
> +       .priv_auto_alloc_size = sizeof(struct msm_serial_data),
> +       .probe = msm_serial_probe,
> +       .ops    = &msm_serial_ops,
> +};
> --
> 2.5.0
>

Regards,
Simon


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