// SPDX-License-Identifier: GPL-2.0+ /* * (C) Copyright 2016 Beniamino Galvani */ #include #include #include #include #include #include #include #include #include struct meson_uart { u32 wfifo; u32 rfifo; u32 control; u32 status; u32 misc; u32 reg5; /* New baud control register */ }; struct meson_serial_plat { struct meson_uart *reg; }; /* AML_UART_STATUS bits */ #define AML_UART_PARITY_ERR BIT(16) #define AML_UART_FRAME_ERR BIT(17) #define AML_UART_TX_FIFO_WERR BIT(18) #define AML_UART_RX_EMPTY BIT(20) #define AML_UART_TX_FULL BIT(21) #define AML_UART_TX_EMPTY BIT(22) #define AML_UART_XMIT_BUSY BIT(25) #define AML_UART_ERR (AML_UART_PARITY_ERR | \ AML_UART_FRAME_ERR | \ AML_UART_TX_FIFO_WERR) /* AML_UART_CONTROL bits */ #define AML_UART_TX_EN BIT(12) #define AML_UART_RX_EN BIT(13) #define AML_UART_TX_RST BIT(22) #define AML_UART_RX_RST BIT(23) #define AML_UART_CLR_ERR BIT(24) /* AML_UART_REG5 bits */ #define AML_UART_REG5_XTAL_DIV2 BIT(27) #define AML_UART_REG5_XTAL_CLK_SEL BIT(26) /* default 0 (div by 3), 1 for no div */ #define AML_UART_REG5_USE_XTAL_CLK BIT(24) /* default 1 (use crystal as clock source) */ #define AML_UART_REG5_USE_NEW_BAUD BIT(23) /* default 1 (use new baud rate register) */ #define AML_UART_REG5_BAUD_MASK 0x7fffff static u32 meson_calc_baud_divisor(ulong src_rate, u32 baud) { /* * Usually src_rate is 24 MHz (from crystal) as clock source for serial * device. Since 8 Mb/s is the maximum supported baud rate, use div by 3 * to derive baud rate. This choice is used also in meson_serial_setbrg. */ return DIV_ROUND_CLOSEST(src_rate / 3, baud) - 1; } static void meson_serial_set_baud(struct meson_uart *uart, ulong src_rate, u32 baud) { /* * Set crystal divided by 3 (regardless of device tree clock property) * as clock source and the corresponding divisor to approximate baud */ u32 divisor = meson_calc_baud_divisor(src_rate, baud); u32 val = AML_UART_REG5_USE_XTAL_CLK | AML_UART_REG5_USE_NEW_BAUD | (divisor & AML_UART_REG5_BAUD_MASK); writel(val, &uart->reg5); } static void meson_serial_init(struct meson_uart *uart) { u32 val; val = readl(&uart->control); val |= (AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR); writel(val, &uart->control); val &= ~(AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR); writel(val, &uart->control); val |= (AML_UART_RX_EN | AML_UART_TX_EN); writel(val, &uart->control); } static int meson_serial_probe(struct udevice *dev) { struct meson_serial_plat *plat = dev_get_plat(dev); struct meson_uart *const uart = plat->reg; struct clk per_clk; int ret = clk_get_by_name(dev, "baud", &per_clk); if (ret) return ret; ulong rate = clk_get_rate(&per_clk); meson_serial_set_baud(uart, rate, CONFIG_BAUDRATE); meson_serial_init(uart); return 0; } static void meson_serial_rx_error(struct udevice *dev) { struct meson_serial_plat *plat = dev_get_plat(dev); struct meson_uart *const uart = plat->reg; u32 val = readl(&uart->control); /* Clear error */ val |= AML_UART_CLR_ERR; writel(val, &uart->control); val &= ~AML_UART_CLR_ERR; writel(val, &uart->control); /* Remove spurious byte from fifo */ readl(&uart->rfifo); } static int meson_serial_getc(struct udevice *dev) { struct meson_serial_plat *plat = dev_get_plat(dev); struct meson_uart *const uart = plat->reg; uint32_t status = readl(&uart->status); if (status & AML_UART_RX_EMPTY) return -EAGAIN; if (status & AML_UART_ERR) { meson_serial_rx_error(dev); return -EIO; } return readl(&uart->rfifo) & 0xff; } static int meson_serial_putc(struct udevice *dev, const char ch) { struct meson_serial_plat *plat = dev_get_plat(dev); struct meson_uart *const uart = plat->reg; if (readl(&uart->status) & AML_UART_TX_FULL) return -EAGAIN; writel(ch, &uart->wfifo); return 0; } static int meson_serial_setbrg(struct udevice *dev, const int baud) { /* * Change device baud rate if baud is reasonable (considering a 23 bit * counter with an 8 MHz clock input) and the actual baud * rate is within 2% of the requested value (2% is arbitrary). */ if (baud < 1 || baud > 8000000) return -EINVAL; struct meson_serial_plat *const plat = dev_get_plat(dev); struct meson_uart *const uart = plat->reg; struct clk per_clk; int ret = clk_get_by_name(dev, "baud", &per_clk); if (ret) return ret; ulong rate = clk_get_rate(&per_clk); u32 divisor = meson_calc_baud_divisor(rate, baud); u32 calc_baud = (rate / 3) / (divisor + 1); u32 calc_err = baud > calc_baud ? baud - calc_baud : calc_baud - baud; if (((calc_err * 100) / baud) > 2) return -EINVAL; meson_serial_set_baud(uart, rate, baud); return 0; } static int meson_serial_pending(struct udevice *dev, bool input) { struct meson_serial_plat *plat = dev_get_plat(dev); struct meson_uart *const uart = plat->reg; uint32_t status = readl(&uart->status); if (input) { if (status & AML_UART_RX_EMPTY) return false; /* * Handle and drop any RX error here to avoid * returning true here when an error byte is in the FIFO */ if (status & AML_UART_ERR) { meson_serial_rx_error(dev); return false; } return true; } else { if (status & AML_UART_TX_EMPTY) return false; return true; } } static int meson_serial_of_to_plat(struct udevice *dev) { struct meson_serial_plat *plat = dev_get_plat(dev); fdt_addr_t addr; addr = dev_read_addr(dev); if (addr == FDT_ADDR_T_NONE) return -EINVAL; plat->reg = (struct meson_uart *)addr; return 0; } static const struct dm_serial_ops meson_serial_ops = { .putc = meson_serial_putc, .pending = meson_serial_pending, .getc = meson_serial_getc, .setbrg = meson_serial_setbrg, }; static const struct udevice_id meson_serial_ids[] = { { .compatible = "amlogic,meson-uart" }, { .compatible = "amlogic,meson-gx-uart" }, { } }; U_BOOT_DRIVER(serial_meson) = { .name = "serial_meson", .id = UCLASS_SERIAL, .of_match = meson_serial_ids, .probe = meson_serial_probe, .ops = &meson_serial_ops, .of_to_plat = meson_serial_of_to_plat, .plat_auto = sizeof(struct meson_serial_plat), }; #ifdef CONFIG_DEBUG_UART_MESON #include static inline void _debug_uart_init(void) { } static inline void _debug_uart_putc(int ch) { struct meson_uart *regs = (struct meson_uart *)CONFIG_VAL(DEBUG_UART_BASE); while (readl(®s->status) & AML_UART_TX_FULL) ; writel(ch, ®s->wfifo); } DEBUG_UART_FUNCS #endif