[PATCH v4] lib: utils: serial: Add Cadence UART driver
Jessica Clarke
jrtc27 at jrtc27.com
Wed Aug 17 18:09:30 PDT 2022
On 18 Aug 2022, at 01:31, Xiang W <wxjstz at 126.com> wrote:
>
> 在 2022-08-17星期三的 23:40 +0800，Jun Liang Tan写道：
>> 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>
>> ---
>>
>> 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;
>> +}
>
> The default of integer division in C language is to discard the fractional part.
> So, the above code is equivalent to:
>
> static inline unsigned int uart_min_clk_divisor(uint64_t in_freq,
> uint64_t max_target_hz)
> {
> return in_freq / max_target_hz;
> }
Not if in_freq is a non-zero multiple of max_target_hz.
I also assume the - 1 in the SiFive UART is a reflection of it biasing
its divisor by 1. Does the Cadence UART actually do that too, or is
this a copy/paste error?
Jess
> Regards,
> Xiang W
>> +
>> +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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