Add Nuvoton BMC NPCM7xx/NPCM8xx uart driver

Signed-off-by: Stanley Chu yschu@nuvoton.com --- Changes in v2: Drop unnecessary outer brackets. Return -EAGAIN if not ready for tx/rx. Add comments. --- drivers/serial/Kconfig | 9 +++ drivers/serial/Makefile | 1 + drivers/serial/serial_npcm.c | 150 +++++++++++++++++++++++++++++++++++ 3 files changed, 160 insertions(+) create mode 100644 drivers/serial/serial_npcm.c

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index 6c8fdda9a0..e67a76a424 100644 --- a/drivers/serial/Kconfig +++ b/drivers/serial/Kconfig @@ -920,6 +920,15 @@ config MPC8XX_CONS depends on MPC8xx default y

+config NPCM_SERIAL + bool "UART driver for Nuvoton NPCM BMC" + depends on DM_SERIAL + help + Select this to enable UART support for Nuvoton BMCs + (NPCM7xx and NPCM8xx). + The driver enables the onboard serial port with 8-N-1 + configuration. + config XEN_SERIAL bool "XEN serial support" depends on XEN diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile index 8168af640f..866495e416 100644 --- a/drivers/serial/Makefile +++ b/drivers/serial/Makefile @@ -73,6 +73,7 @@ obj-$(CONFIG_OWL_SERIAL) += serial_owl.o obj-$(CONFIG_OMAP_SERIAL) += serial_omap.o obj-$(CONFIG_MTK_SERIAL) += serial_mtk.o obj-$(CONFIG_MT7620_SERIAL) += serial_mt7620.o +obj-$(CONFIG_NPCM_SERIAL) += serial_npcm.o obj-$(CONFIG_SIFIVE_SERIAL) += serial_sifive.o obj-$(CONFIG_XEN_SERIAL) += serial_xen.o

diff --git a/drivers/serial/serial_npcm.c b/drivers/serial/serial_npcm.c new file mode 100644 index 0000000000..0c6f0410cf --- /dev/null +++ b/drivers/serial/serial_npcm.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (c) 2021 Nuvoton Technology Corp. + */ + +#include <common.h> +#include <clk.h> +#include <dm.h> +#include <serial.h> + +struct npcm_uart { + union { + u32 rbr; /* Receive Buffer Register */ + u32 thr; /* Transmit Holding Register */ + u32 dll; /* Divisor Latch (Low Byte) Register */ + }; + union { + u32 ier; /* Interrupt Enable Register */ + u32 dlm; /* Divisor Latch (Low Byte) Register */ + }; + union { + u32 iir; /* Interrupt Identification Register */ + u32 fcr; /* FIFO Control Register */ + }; + u32 lcr; /* Line Control Register */ + u32 mcr; /* Modem Control Register */ + u32 lsr; /* Line Status Control Register */ + u32 msr; /* Modem Status Register */ + u32 tor; /* Timeout Register */ +}; + +#define LCR_WLS_8BITS 3 /* 8-bit word length select */ +#define FCR_TFR BIT(2) /* TxFIFO reset */ +#define FCR_RFR BIT(1) /* RxFIFO reset */ +#define FCR_FME BIT(0) /* FIFO mode enable */ +#define LSR_THRE BIT(5) /* Status of TxFIFO empty */ +#define LSR_RFDR BIT(0) /* Status of RxFIFO data ready */ +#define LCR_DLAB BIT(7) /* Divisor latch access bit */ + +struct npcm_serial_plat { + struct npcm_uart *reg; + u32 uart_clk; /* frequency of uart clock source */ +}; + +static int npcm_serial_pending(struct udevice *dev, bool input) +{ + struct npcm_serial_plat *plat = dev_get_plat(dev); + struct npcm_uart *uart = plat->reg; + + if (input) + return readb(&uart->lsr) & LSR_RFDR ? 1 : 0; + else + return readb(&uart->lsr) & LSR_THRE ? 0 : 1; +} + +static int npcm_serial_putc(struct udevice *dev, const char ch) +{ + struct npcm_serial_plat *plat = dev_get_plat(dev); + struct npcm_uart *uart = plat->reg; + + if (!(readb(&uart->lsr) & LSR_THRE)) + return -EAGAIN; + + writeb(ch, &uart->thr); + + return 0; +} + +static int npcm_serial_getc(struct udevice *dev) +{ + struct npcm_serial_plat *plat = dev_get_plat(dev); + struct npcm_uart *uart = plat->reg; + + if (!(readb(&uart->lsr) & LSR_RFDR)) + return -EAGAIN; + + return readb(&uart->rbr); +} + +static int npcm_serial_setbrg(struct udevice *dev, int baudrate) +{ + struct npcm_serial_plat *plat = dev_get_plat(dev); + struct npcm_uart *uart = plat->reg; + u16 divisor; + + /* BaudOut = UART Clock / (16 * [Divisor + 2]) */ + divisor = DIV_ROUND_CLOSEST(plat->uart_clk, 16 * baudrate + 2) - 2; + + setbits_8(&uart->lcr, LCR_DLAB); + writeb(divisor & 0xff, &uart->dll); + writeb(divisor >> 8, &uart->dlm); + clrbits_8(&uart->lcr, LCR_DLAB); + + return 0; +} + +static int npcm_serial_probe(struct udevice *dev) +{ + struct npcm_serial_plat *plat = dev_get_plat(dev); + struct npcm_uart *uart = plat->reg; + struct clk clk; + u32 freq; + int ret; + + plat->reg = dev_read_addr_ptr(dev); + freq = dev_read_u32_default(dev, "clock-frequency", 0); + + ret = clk_get_by_index(dev, 0, &clk); + if (ret < 0) + return ret; + + ret = clk_set_rate(&clk, freq); + if (ret < 0) + return ret; + plat->uart_clk = ret; + + /* Disable all interrupt */ + writeb(0, &uart->ier); + + /* Set 8 bit, 1 stop, no parity */ + writeb(LCR_WLS_8BITS, &uart->lcr); + + /* Reset RX/TX FIFO */ + writeb(FCR_FME | FCR_RFR | FCR_TFR, &uart->fcr); + + return 0; +} + +static const struct dm_serial_ops npcm_serial_ops = { + .getc = npcm_serial_getc, + .setbrg = npcm_serial_setbrg, + .putc = npcm_serial_putc, + .pending = npcm_serial_pending, +}; + +static const struct udevice_id npcm_serial_ids[] = { + { .compatible = "nuvoton,npcm750-uart" }, + { .compatible = "nuvoton,npcm845-uart" }, + { } +}; + +U_BOOT_DRIVER(serial_npcm) = { + .name = "serial_npcm", + .id = UCLASS_SERIAL, + .of_match = npcm_serial_ids, + .plat_auto = sizeof(struct npcm_serial_plat), + .probe = npcm_serial_probe, + .ops = &npcm_serial_ops, + .flags = DM_FLAG_PRE_RELOC, +};