diff options
Diffstat (limited to 'roms/u-boot/drivers/serial/serial_sti_asc.c')
| -rw-r--r-- | roms/u-boot/drivers/serial/serial_sti_asc.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/roms/u-boot/drivers/serial/serial_sti_asc.c b/roms/u-boot/drivers/serial/serial_sti_asc.c new file mode 100644 index 000000000..2cada4efb --- /dev/null +++ b/roms/u-boot/drivers/serial/serial_sti_asc.c @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Support for Serial I/O using STMicroelectronics' on-chip ASC. + * + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved + * Author(s): Patrice Chotard, <patrice.chotard@foss.st.com> for STMicroelectronics. + */ + +#include <common.h> +#include <dm.h> +#include <log.h> +#include <serial.h> +#include <asm/global_data.h> +#include <asm/io.h> +#include <linux/bitops.h> + +DECLARE_GLOBAL_DATA_PTR; + +#define BAUDMODE 0x00001000 +#define RXENABLE 0x00000100 +#define RUN 0x00000080 +#define MODE 0x00000001 +#define MODE_8BIT 0x0001 +#define STOP_1BIT 0x0008 +#define PARITYODD 0x0020 + +#define STA_TF BIT(9) +#define STA_RBF BIT(0) + +struct sti_asc_uart { + u32 baudrate; + u32 txbuf; + u32 rxbuf; + u32 control; + u32 inten; + u32 status; + u32 guardtime; + u32 timeout; + u32 txreset; + u32 rxreset; +}; + +struct sti_asc_serial { + /* address of registers in physical memory */ + struct sti_asc_uart *regs; +}; + +/* Values for the BAUDRATE Register */ +#define PCLK (200ul * 1000000ul) +#define BAUDRATE_VAL_M0(bps) (PCLK / (16 * (bps))) +#define BAUDRATE_VAL_M1(bps) ((bps * (1 << 14)) + (1<<13)) / (PCLK/(1 << 6)) + +/* + * MODE 0 + * ICCLK + * ASCBaudRate = ---------------- + * baudrate * 16 + * + * MODE 1 + * baudrate * 16 * 2^16 + * ASCBaudRate = ------------------------ + * ICCLK + * + * NOTE: + * Mode 1 should be used for baudrates of 19200, and above, as it + * has a lower deviation error than Mode 0 for higher frequencies. + * Mode 0 should be used for all baudrates below 19200. + */ + +static int sti_asc_pending(struct udevice *dev, bool input) +{ + struct sti_asc_serial *priv = dev_get_priv(dev); + struct sti_asc_uart *const uart = priv->regs; + unsigned long status; + + status = readl(&uart->status); + if (input) + return status & STA_RBF; + else + return status & STA_TF; +} + +static int _sti_asc_serial_setbrg(struct sti_asc_uart *uart, int baudrate) +{ + unsigned long val; + int t, mode = 1; + + switch (baudrate) { + case 9600: + t = BAUDRATE_VAL_M0(9600); + mode = 0; + break; + case 19200: + t = BAUDRATE_VAL_M1(19200); + break; + case 38400: + t = BAUDRATE_VAL_M1(38400); + break; + case 57600: + t = BAUDRATE_VAL_M1(57600); + break; + default: + debug("ASC: unsupported baud rate: %d, using 115200 instead.\n", + baudrate); + case 115200: + t = BAUDRATE_VAL_M1(115200); + break; + } + + /* disable the baudrate generator */ + val = readl(&uart->control); + writel(val & ~RUN, &uart->control); + + /* set baud generator reload value */ + writel(t, &uart->baudrate); + /* reset the RX & TX buffers */ + writel(1, &uart->txreset); + writel(1, &uart->rxreset); + + /* set baud generator mode */ + if (mode) + val |= BAUDMODE; + + /* finally, write value and enable ASC */ + writel(val, &uart->control); + + return 0; +} + +/* called to adjust baud-rate */ +static int sti_asc_serial_setbrg(struct udevice *dev, int baudrate) +{ + struct sti_asc_serial *priv = dev_get_priv(dev); + struct sti_asc_uart *const uart = priv->regs; + + return _sti_asc_serial_setbrg(uart, baudrate); +} + +/* blocking function, that returns next char */ +static int sti_asc_serial_getc(struct udevice *dev) +{ + struct sti_asc_serial *priv = dev_get_priv(dev); + struct sti_asc_uart *const uart = priv->regs; + + /* polling wait: for a char to be read */ + if (!sti_asc_pending(dev, true)) + return -EAGAIN; + + return readl(&uart->rxbuf); +} + +/* write write out a single char */ +static int sti_asc_serial_putc(struct udevice *dev, const char c) +{ + struct sti_asc_serial *priv = dev_get_priv(dev); + struct sti_asc_uart *const uart = priv->regs; + + /* wait till safe to write next char */ + if (sti_asc_pending(dev, false)) + return -EAGAIN; + + /* finally, write next char */ + writel(c, &uart->txbuf); + + return 0; +} + +/* initialize the ASC */ +static int sti_asc_serial_probe(struct udevice *dev) +{ + struct sti_asc_serial *priv = dev_get_priv(dev); + unsigned long val; + fdt_addr_t base; + + base = dev_read_addr(dev); + if (base == FDT_ADDR_T_NONE) + return -EINVAL; + + priv->regs = (struct sti_asc_uart *)base; + sti_asc_serial_setbrg(dev, gd->baudrate); + + /* + * build up the value to be written to CONTROL + * set character length, bit stop number, odd parity + */ + val = RXENABLE | RUN | MODE_8BIT | STOP_1BIT | PARITYODD; + writel(val, &priv->regs->control); + + return 0; +} + +static const struct dm_serial_ops sti_asc_serial_ops = { + .putc = sti_asc_serial_putc, + .pending = sti_asc_pending, + .getc = sti_asc_serial_getc, + .setbrg = sti_asc_serial_setbrg, +}; + +static const struct udevice_id sti_serial_of_match[] = { + { .compatible = "st,asc" }, + { } +}; + +U_BOOT_DRIVER(serial_sti_asc) = { + .name = "serial_sti_asc", + .id = UCLASS_SERIAL, + .of_match = sti_serial_of_match, + .ops = &sti_asc_serial_ops, + .probe = sti_asc_serial_probe, + .priv_auto = sizeof(struct sti_asc_serial), +}; + |