[PATCH v4] lib: utils: serial: Add Cadence UART driver
Anup Patel
anup at brainfault.org
Sun Aug 21 20:08:40 PDT 2022
On Wed, Aug 17, 2022 at 9:11 PM Jun Liang Tan
<junliang.tan at linux.starfivetech.com> wrote:
>
> Add Cadence UART driver
>
> Signed-off-by: Jun Liang Tan <junliang.tan at linux.starfivetech.com>
> Signed-off-by: Wei Liang Lim <weiliang.lim at linux.starfivetech.com>
Overall, this looks good except the divide-by-zero question raised by
other folks in uart_min_clk_divisor().
Reviewed-by: Anup Patel <anup at brainfault.org>
Regards,
Anup
> ---
>
> Changes in v4:
> - Add changelog
> - Check for possible divide-by-zero in uart_min_clk_divisor() by
> referring to the fix in commit f27203525aa2fc20d0074feb892a6f8433f84e3a
> - Cosmetic changes
>
> Changes in v3:
> - Place #define register name in ascending order of register offset
> - Change #define register name to match manual register name
> - #define register flags in a way associate with their register
> - Cosmetic changes
>
> Changes in v2:
> - Rename fdt_parse_uart8250_node() to fdt_parse_uart_node() and make
> neccessary changes in functions that call it
> - Align patch with the latest OpenSBI sources
>
> include/sbi_utils/fdt/fdt_helper.h | 4 +-
> include/sbi_utils/serial/cadence-uart.h | 16 +++
> lib/utils/fdt/fdt_helper.c | 6 +-
> lib/utils/serial/Kconfig | 9 ++
> lib/utils/serial/cadence-uart.c | 128 ++++++++++++++++++++++++
> lib/utils/serial/fdt_serial_cadence.c | 35 +++++++
> lib/utils/serial/fdt_serial_uart8250.c | 2 +-
> lib/utils/serial/objects.mk | 4 +
> platform/generic/configs/defconfig | 1 +
> 9 files changed, 199 insertions(+), 6 deletions(-)
> create mode 100644 include/sbi_utils/serial/cadence-uart.h
> create mode 100644 lib/utils/serial/cadence-uart.c
> create mode 100644 lib/utils/serial/fdt_serial_cadence.c
>
> diff --git a/include/sbi_utils/fdt/fdt_helper.h b/include/sbi_utils/fdt/fdt_helper.h
> index c60af35..bcd4996 100644
> --- a/include/sbi_utils/fdt/fdt_helper.h
> +++ b/include/sbi_utils/fdt/fdt_helper.h
> @@ -65,8 +65,8 @@ int fdt_parse_shakti_uart_node(void *fdt, int nodeoffset,
> int fdt_parse_sifive_uart_node(void *fdt, int nodeoffset,
> struct platform_uart_data *uart);
>
> -int fdt_parse_uart8250_node(void *fdt, int nodeoffset,
> - struct platform_uart_data *uart);
> +int fdt_parse_uart_node(void *fdt, int nodeoffset,
> + struct platform_uart_data *uart);
>
> int fdt_parse_uart8250(void *fdt, struct platform_uart_data *uart,
> const char *compatible);
> diff --git a/include/sbi_utils/serial/cadence-uart.h b/include/sbi_utils/serial/cadence-uart.h
> new file mode 100644
> index 0000000..e75fb95
> --- /dev/null
> +++ b/include/sbi_utils/serial/cadence-uart.h
> @@ -0,0 +1,16 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2022 StarFive Technology Co., Ltd.
> + *
> + * Author: Jun Liang Tan <junliang.tan at linux.starfivetech.com>
> + */
> +
> +#ifndef __SERIAL_CADENCE_UART_H__
> +#define __SERIAL_CADENCE_UART_H__
> +
> +#include <sbi/sbi_types.h>
> +
> +int cadence_uart_init(unsigned long base, u32 in_freq, u32 baudrate);
> +
> +#endif
> diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
> index c6abf80..6a75d6f 100644
> --- a/lib/utils/fdt/fdt_helper.c
> +++ b/lib/utils/fdt/fdt_helper.c
> @@ -401,8 +401,8 @@ int fdt_parse_sifive_uart_node(void *fdt, int nodeoffset,
> return 0;
> }
>
> -int fdt_parse_uart8250_node(void *fdt, int nodeoffset,
> - struct platform_uart_data *uart)
> +int fdt_parse_uart_node(void *fdt, int nodeoffset,
> + struct platform_uart_data *uart)
> {
> int len, rc;
> const fdt32_t *val;
> @@ -447,7 +447,7 @@ int fdt_parse_uart8250(void *fdt, struct platform_uart_data *uart,
> if (nodeoffset < 0)
> return nodeoffset;
>
> - return fdt_parse_uart8250_node(fdt, nodeoffset, uart);
> + return fdt_parse_uart_node(fdt, nodeoffset, uart);
> }
>
> int fdt_parse_xlnx_uartlite_node(void *fdt, int nodeoffset,
> diff --git a/lib/utils/serial/Kconfig b/lib/utils/serial/Kconfig
> index 152060d..6e425f2 100644
> --- a/lib/utils/serial/Kconfig
> +++ b/lib/utils/serial/Kconfig
> @@ -9,6 +9,11 @@ config FDT_SERIAL
>
> if FDT_SERIAL
>
> +config FDT_SERIAL_CADENCE
> + bool "Cadence UART FDT driver"
> + select SERIAL_CADENCE
> + default n
> +
> config FDT_SERIAL_GAISLER
> bool "Gaisler UART FDT driver"
> select SERIAL_GAISLER
> @@ -46,6 +51,10 @@ config FDT_SERIAL_XILINX_UARTLITE
>
> endif
>
> +config SERIAL_CADENCE
> + bool "Cadence UART support"
> + default n
> +
> config SERIAL_GAISLER
> bool "Gaisler UART support"
> default n
> diff --git a/lib/utils/serial/cadence-uart.c b/lib/utils/serial/cadence-uart.c
> new file mode 100644
> index 0000000..8a2b6ba
> --- /dev/null
> +++ b/lib/utils/serial/cadence-uart.c
> @@ -0,0 +1,128 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2022 StarFive Technology Co., Ltd.
> + *
> + * Author: Jun Liang Tan <junliang.tan at linux.starfivetech.com>
> + */
> +
> +#include <sbi/riscv_io.h>
> +#include <sbi/sbi_console.h>
> +#include <sbi_utils/serial/cadence-uart.h>
> +
> +/* clang-format off */
> +
> +#define UART_REG_CTRL 0x00
> +#define UART_REG_MODE 0x04
> +#define UART_REG_IDR 0x0C
> +#define UART_REG_BRGR 0x18
> +#define UART_REG_CSR 0x2C
> +#define UART_REG_RFIFO_TFIFO 0x30
> +#define UART_REG_BDIVR 0x34
> +
> +#define UART_CTRL_RXRES 0x00000001
> +#define UART_CTRL_TXRES 0x00000002
> +#define UART_CTRL_RXEN 0x00000004
> +#define UART_CTRL_RXDIS 0x00000008
> +#define UART_CTRL_TXEN 0x00000010
> +#define UART_CTRL_TXDIS 0x00000020
> +
> +#define UART_MODE_PAR_NONE 0x00000020 /* No parity set */
> +
> +#define UART_BRGR_CD_CLKDIVISOR 0x00000001 /* baud_sample = sel_clk */
> +
> +#define UART_CSR_REMPTY 0x00000002
> +#define UART_CSR_TFUL 0x00000010
> +
> +/* clang-format on */
> +
> +static volatile void *uart_base;
> +static u32 uart_in_freq;
> +static u32 uart_baudrate;
> +
> +/*
> + * Find minimum divisor divides in_freq to max_target_hz;
> + * Based on SiFive UART driver (sifive-uart.c)
> + */
> +static inline unsigned int uart_min_clk_divisor(uint64_t in_freq,
> + uint64_t max_target_hz)
> +{
> + uint64_t quotient = (in_freq + max_target_hz - 1) / (max_target_hz);
> +
> + /* Avoid underflow */
> + if (quotient == 0)
> + return 0;
> + else
> + return quotient - 1;
> +}
> +
> +static u32 get_reg(u32 offset)
> +{
> + return readl(uart_base + offset);
> +}
> +
> +static void set_reg(u32 offset, u32 val)
> +{
> + writel(val, uart_base + offset);
> +}
> +
> +static void cadence_uart_putc(char ch)
> +{
> + while (get_reg(UART_REG_CSR) & UART_CSR_TFUL)
> + ;
> +
> + set_reg(UART_REG_RFIFO_TFIFO, ch);
> +}
> +
> +static int cadence_uart_getc(void)
> +{
> + u32 ret = get_reg(UART_REG_CSR);
> +
> + if (!(ret & UART_CSR_REMPTY))
> + return get_reg(UART_REG_RFIFO_TFIFO);
> +
> + return -1;
> +}
> +
> +static struct sbi_console_device cadence_console = {
> + .name = "cadence_uart",
> + .console_putc = cadence_uart_putc,
> + .console_getc = cadence_uart_getc
> +};
> +
> +int cadence_uart_init(unsigned long base, u32 in_freq, u32 baudrate)
> +{
> + uart_base = (volatile void *)base;
> + uart_in_freq = in_freq;
> + uart_baudrate = baudrate;
> +
> + /* Disable interrupts */
> + set_reg(UART_REG_IDR, 0xFFFFFFFF);
> +
> + /* Disable TX RX */
> + set_reg(UART_REG_CTRL, UART_CTRL_TXDIS | UART_CTRL_RXDIS);
> +
> + /* Configure baudrate */
> + if (in_freq && baudrate) {
> + set_reg(UART_REG_BRGR, UART_BRGR_CD_CLKDIVISOR);
> + set_reg(UART_REG_BDIVR,
> + uart_min_clk_divisor(in_freq, baudrate));
> + }
> +
> + /* Software reset TX RX data path and enable TX RX */
> + set_reg(UART_REG_CTRL, UART_CTRL_TXRES | UART_CTRL_RXRES
> + | UART_CTRL_TXEN | UART_CTRL_RXEN);
> +
> + /*
> + * Set:
> + * 1 stop bit, bits[07:06] = 0x00,
> + * no parity set, bits[05:03] = 0x100,
> + * 8 bits character length, bits[02:01] = 0x00,
> + * sel_clk = uart_clk, bit[0] = 0x0
> + */
> + set_reg(UART_REG_MODE, UART_MODE_PAR_NONE);
> +
> + sbi_console_set_device(&cadence_console);
> +
> + return 0;
> +}
> diff --git a/lib/utils/serial/fdt_serial_cadence.c b/lib/utils/serial/fdt_serial_cadence.c
> new file mode 100644
> index 0000000..946e533
> --- /dev/null
> +++ b/lib/utils/serial/fdt_serial_cadence.c
> @@ -0,0 +1,35 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2022 StarFive Technology Co., Ltd.
> + *
> + * Author: Jun Liang Tan <junliang.tan at linux.starfivetech.com>
> + */
> +
> +#include <sbi_utils/fdt/fdt_helper.h>
> +#include <sbi_utils/serial/fdt_serial.h>
> +#include <sbi_utils/serial/cadence-uart.h>
> +
> +static int serial_cadence_init(void *fdt, int nodeoff,
> + const struct fdt_match *match)
> +{
> + int rc;
> + struct platform_uart_data uart = { 0 };
> +
> + rc = fdt_parse_uart_node(fdt, nodeoff, &uart);
> + if (rc)
> + return rc;
> +
> + return cadence_uart_init(uart.addr, uart.freq, uart.baud);
> +}
> +
> +static const struct fdt_match serial_cadence_match[] = {
> + { .compatible = "cdns,uart-r1p12" },
> + { .compatible = "starfive,jh8100-uart" },
> + { },
> +};
> +
> +struct fdt_serial fdt_serial_cadence = {
> + .match_table = serial_cadence_match,
> + .init = serial_cadence_init
> +};
> diff --git a/lib/utils/serial/fdt_serial_uart8250.c b/lib/utils/serial/fdt_serial_uart8250.c
> index 0b95f2d..7b5d6a4 100644
> --- a/lib/utils/serial/fdt_serial_uart8250.c
> +++ b/lib/utils/serial/fdt_serial_uart8250.c
> @@ -17,7 +17,7 @@ static int serial_uart8250_init(void *fdt, int nodeoff,
> int rc;
> struct platform_uart_data uart = { 0 };
>
> - rc = fdt_parse_uart8250_node(fdt, nodeoff, &uart);
> + rc = fdt_parse_uart_node(fdt, nodeoff, &uart);
> if (rc)
> return rc;
>
> diff --git a/lib/utils/serial/objects.mk b/lib/utils/serial/objects.mk
> index fa9f5a3..efb1d9e 100644
> --- a/lib/utils/serial/objects.mk
> +++ b/lib/utils/serial/objects.mk
> @@ -10,6 +10,9 @@
> libsbiutils-objs-$(CONFIG_FDT_SERIAL) += serial/fdt_serial.o
> libsbiutils-objs-$(CONFIG_FDT_SERIAL) += serial/fdt_serial_drivers.o
>
> +carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_CADENCE) += fdt_serial_cadence
> +libsbiutils-objs-$(CONFIG_FDT_SERIAL_CADENCE) += serial/fdt_serial_cadence.o
> +
> carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_GAISLER) += fdt_serial_gaisler
> libsbiutils-objs-$(CONFIG_FDT_SERIAL_GAISLER) += serial/fdt_serial_gaisler.o
>
> @@ -31,6 +34,7 @@ libsbiutils-objs-$(CONFIG_FDT_SERIAL_UART8250) += serial/fdt_serial_uart8250.o
> carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_XILINX_UARTLITE) += fdt_serial_xlnx_uartlite
> libsbiutils-objs-$(CONFIG_FDT_SERIAL_XILINX_UARTLITE) += serial/fdt_serial_xlnx_uartlite.o
>
> +libsbiutils-objs-$(CONFIG_SERIAL_CADENCE) += serial/cadence-uart.o
> libsbiutils-objs-$(CONFIG_SERIAL_GAISLER) += serial/gaisler-uart.o
> libsbiutils-objs-$(CONFIG_SERIAL_SHAKTI) += serial/shakti-uart.o
> libsbiutils-objs-$(CONFIG_SERIAL_SIFIVE) += serial/sifive-uart.o
> diff --git a/platform/generic/configs/defconfig b/platform/generic/configs/defconfig
> index 2a75394..e324173 100644
> --- a/platform/generic/configs/defconfig
> +++ b/platform/generic/configs/defconfig
> @@ -18,6 +18,7 @@ CONFIG_FDT_RESET_SIFIVE_TEST=y
> CONFIG_FDT_RESET_SUNXI_WDT=y
> CONFIG_FDT_RESET_THEAD=y
> CONFIG_FDT_SERIAL=y
> +CONFIG_FDT_SERIAL_CADENCE=y
> CONFIG_FDT_SERIAL_GAISLER=y
> CONFIG_FDT_SERIAL_HTIF=y
> CONFIG_FDT_SERIAL_SHAKTI=y
> --
> 2.37.1
>
>
>
> --
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