// SPDX-License-Identifier: GPL-2.0+ /* * SiFive UART driver * Copyright (C) 2018 Paul Walmsley * Copyright (C) 2018-2019 SiFive * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * Based partially on: * - drivers/tty/serial/pxa.c * - drivers/tty/serial/amba-pl011.c * - drivers/tty/serial/uartlite.c * - drivers/tty/serial/omap-serial.c * - drivers/pwm/pwm-sifive.c * * See the following sources for further documentation: * - Chapter 19 "Universal Asynchronous Receiver/Transmitter (UART)" of * SiFive FE310-G000 v2p3 * - The tree/master/src/main/scala/devices/uart directory of * https://github.com/sifive/sifive-blocks/ * * The SiFive UART design is not 8250-compatible. The following common * features are not supported: * - Word lengths other than 8 bits * - Break handling * - Parity * - Flow control * - Modem signals (DSR, RI, etc.) * On the other hand, the design is free from the baggage of the 8250 * programming model. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Register offsets */ /* TXDATA */ #define SIFIVE_SERIAL_TXDATA_OFFS 0x0 #define SIFIVE_SERIAL_TXDATA_FULL_SHIFT 31 #define SIFIVE_SERIAL_TXDATA_FULL_MASK (1 << SIFIVE_SERIAL_TXDATA_FULL_SHIFT) #define SIFIVE_SERIAL_TXDATA_DATA_SHIFT 0 #define SIFIVE_SERIAL_TXDATA_DATA_MASK (0xff << SIFIVE_SERIAL_TXDATA_DATA_SHIFT) /* RXDATA */ #define SIFIVE_SERIAL_RXDATA_OFFS 0x4 #define SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT 31 #define SIFIVE_SERIAL_RXDATA_EMPTY_MASK (1 << SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT) #define SIFIVE_SERIAL_RXDATA_DATA_SHIFT 0 #define SIFIVE_SERIAL_RXDATA_DATA_MASK (0xff << SIFIVE_SERIAL_RXDATA_DATA_SHIFT) /* TXCTRL */ #define SIFIVE_SERIAL_TXCTRL_OFFS 0x8 #define SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT 16 #define SIFIVE_SERIAL_TXCTRL_TXCNT_MASK (0x7 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT) #define SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT 1 #define SIFIVE_SERIAL_TXCTRL_NSTOP_MASK (1 << SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT) #define SIFIVE_SERIAL_TXCTRL_TXEN_SHIFT 0 #define SIFIVE_SERIAL_TXCTRL_TXEN_MASK (1 << SIFIVE_SERIAL_TXCTRL_TXEN_SHIFT) /* RXCTRL */ #define SIFIVE_SERIAL_RXCTRL_OFFS 0xC #define SIFIVE_SERIAL_RXCTRL_RXCNT_SHIFT 16 #define SIFIVE_SERIAL_RXCTRL_RXCNT_MASK (0x7 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT) #define SIFIVE_SERIAL_RXCTRL_RXEN_SHIFT 0 #define SIFIVE_SERIAL_RXCTRL_RXEN_MASK (1 << SIFIVE_SERIAL_RXCTRL_RXEN_SHIFT) /* IE */ #define SIFIVE_SERIAL_IE_OFFS 0x10 #define SIFIVE_SERIAL_IE_RXWM_SHIFT 1 #define SIFIVE_SERIAL_IE_RXWM_MASK (1 << SIFIVE_SERIAL_IE_RXWM_SHIFT) #define SIFIVE_SERIAL_IE_TXWM_SHIFT 0 #define SIFIVE_SERIAL_IE_TXWM_MASK (1 << SIFIVE_SERIAL_IE_TXWM_SHIFT) /* IP */ #define SIFIVE_SERIAL_IP_OFFS 0x14 #define SIFIVE_SERIAL_IP_RXWM_SHIFT 1 #define SIFIVE_SERIAL_IP_RXWM_MASK (1 << SIFIVE_SERIAL_IP_RXWM_SHIFT) #define SIFIVE_SERIAL_IP_TXWM_SHIFT 0 #define SIFIVE_SERIAL_IP_TXWM_MASK (1 << SIFIVE_SERIAL_IP_TXWM_SHIFT) /* DIV */ #define SIFIVE_SERIAL_DIV_OFFS 0x18 #define SIFIVE_SERIAL_DIV_DIV_SHIFT 0 #define SIFIVE_SERIAL_DIV_DIV_MASK (0xffff << SIFIVE_SERIAL_IP_DIV_SHIFT) /* * Config macros */ /* * SIFIVE_SERIAL_MAX_PORTS: maximum number of UARTs on a device that can * host a serial console */ #define SIFIVE_SERIAL_MAX_PORTS 8 /* * SIFIVE_DEFAULT_BAUD_RATE: default baud rate that the driver should * configure itself to use */ #define SIFIVE_DEFAULT_BAUD_RATE 115200 /* SIFIVE_SERIAL_NAME: our driver's name that we pass to the operating system */ #define SIFIVE_SERIAL_NAME "sifive-serial" /* SIFIVE_TTY_PREFIX: tty name prefix for SiFive serial ports */ #define SIFIVE_TTY_PREFIX "ttySIF" /* SIFIVE_TX_FIFO_DEPTH: depth of the TX FIFO (in bytes) */ #define SIFIVE_TX_FIFO_DEPTH 8 /* SIFIVE_RX_FIFO_DEPTH: depth of the TX FIFO (in bytes) */ #define SIFIVE_RX_FIFO_DEPTH 8 #if (SIFIVE_TX_FIFO_DEPTH != SIFIVE_RX_FIFO_DEPTH) #error Driver does not support configurations with different TX, RX FIFO sizes #endif /* * */ /** * sifive_serial_port - driver-specific data extension to struct uart_port * @port: struct uart_port embedded in this struct * @dev: struct device * * @ier: shadowed copy of the interrupt enable register * @clkin_rate: input clock to the UART IP block. * @baud_rate: UART serial line rate (e.g., 115200 baud) * @clk_notifier: clock rate change notifier for upstream clock changes * * Configuration data specific to this SiFive UART. */ struct sifive_serial_port { struct uart_port port; struct device *dev; unsigned char ier; unsigned long clkin_rate; unsigned long baud_rate; struct clk *clk; struct notifier_block clk_notifier; }; /* * Structure container-of macros */ #define port_to_sifive_serial_port(p) (container_of((p), \ struct sifive_serial_port, \ port)) #define notifier_to_sifive_serial_port(nb) (container_of((nb), \ struct sifive_serial_port, \ clk_notifier)) /* * Forward declarations */ static void sifive_serial_stop_tx(struct uart_port *port); /* * Internal functions */ /** * __ssp_early_writel() - write to a SiFive serial port register (early) * @port: pointer to a struct uart_port record * @offs: register address offset from the IP block base address * @v: value to write to the register * * Given a pointer @port to a struct uart_port record, write the value * @v to the IP block register address offset @offs. This function is * intended for early console use. * * Context: Intended to be used only by the earlyconsole code. */ static void __ssp_early_writel(u32 v, u16 offs, struct uart_port *port) { writel_relaxed(v, port->membase + offs); } /** * __ssp_early_readl() - read from a SiFive serial port register (early) * @port: pointer to a struct uart_port record * @offs: register address offset from the IP block base address * * Given a pointer @port to a struct uart_port record, read the * contents of the IP block register located at offset @offs from the * IP block base and return it. This function is intended for early * console use. * * Context: Intended to be called only by the earlyconsole code or by * __ssp_readl() or __ssp_writel() (in this driver) * * Returns: the register value read from the UART. */ static u32 __ssp_early_readl(struct uart_port *port, u16 offs) { return readl_relaxed(port->membase + offs); } /** * __ssp_writel() - write to a SiFive serial port register * @v: value to write to the register * @offs: register address offset from the IP block base address * @ssp: pointer to a struct sifive_serial_port record * * Write the value @v to the IP block register located at offset @offs from the * IP block base, given a pointer @ssp to a struct sifive_serial_port record. * * Context: Any context. */ static void __ssp_writel(u32 v, u16 offs, struct sifive_serial_port *ssp) { __ssp_early_writel(v, offs, &ssp->port); } /** * __ssp_readl() - read from a SiFive serial port register * @ssp: pointer to a struct sifive_serial_port record * @offs: register address offset from the IP block base address * * Read the contents of the IP block register located at offset @offs from the * IP block base, given a pointer @ssp to a struct sifive_serial_port record. * * Context: Any context. * * Returns: the value of the UART register */ static u32 __ssp_readl(struct sifive_serial_port *ssp, u16 offs) { return __ssp_early_readl(&ssp->port, offs); } /** * sifive_serial_is_txfifo_full() - is the TXFIFO full? * @ssp: pointer to a struct sifive_serial_port * * Read the transmit FIFO "full" bit, returning a non-zero value if the * TX FIFO is full, or zero if space remains. Intended to be used to prevent * writes to the TX FIFO when it's full. * * Returns: SIFIVE_SERIAL_TXDATA_FULL_MASK (non-zero) if the transmit FIFO * is full, or 0 if space remains. */ static int sifive_serial_is_txfifo_full(struct sifive_serial_port *ssp) { return __ssp_readl(ssp, SIFIVE_SERIAL_TXDATA_OFFS) & SIFIVE_SERIAL_TXDATA_FULL_MASK; } /** * __ssp_transmit_char() - enqueue a byte to transmit onto the TX FIFO * @ssp: pointer to a struct sifive_serial_port * @ch: character to transmit * * Enqueue a byte @ch onto the transmit FIFO, given a pointer @ssp to the * struct sifive_serial_port * to transmit on. Caller should first check to * ensure that the TXFIFO has space; see sifive_serial_is_txfifo_full(). * * Context: Any context. */ static void __ssp_transmit_char(struct sifive_serial_port *ssp, int ch) { __ssp_writel(ch, SIFIVE_SERIAL_TXDATA_OFFS, ssp); } /** * __ssp_transmit_chars() - enqueue multiple bytes onto the TX FIFO * @ssp: pointer to a struct sifive_serial_port * * Transfer up to a TX FIFO size's worth of characters from the Linux serial * transmit buffer to the SiFive UART TX FIFO. * * Context: Any context. Expects @ssp->port.lock to be held by caller. */ static void __ssp_transmit_chars(struct sifive_serial_port *ssp) { struct circ_buf *xmit = &ssp->port.state->xmit; int count; if (ssp->port.x_char) { __ssp_transmit_char(ssp, ssp->port.x_char); ssp->port.icount.tx++; ssp->port.x_char = 0; return; } if (uart_circ_empty(xmit) || uart_tx_stopped(&ssp->port)) { sifive_serial_stop_tx(&ssp->port); return; } count = SIFIVE_TX_FIFO_DEPTH; do { __ssp_transmit_char(ssp, xmit->buf[xmit->tail]); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); ssp->port.icount.tx++; if (uart_circ_empty(xmit)) break; } while (--count > 0); if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(&ssp->port); if (uart_circ_empty(xmit)) sifive_serial_stop_tx(&ssp->port); } /** * __ssp_enable_txwm() - enable transmit watermark interrupts * @ssp: pointer to a struct sifive_serial_port * * Enable interrupt generation when the transmit FIFO watermark is reached * on the SiFive UART referred to by @ssp. */ static void __ssp_enable_txwm(struct sifive_serial_port *ssp) { if (ssp->ier & SIFIVE_SERIAL_IE_TXWM_MASK) return; ssp->ier |= SIFIVE_SERIAL_IE_TXWM_MASK; __ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp); } /** * __ssp_enable_rxwm() - enable receive watermark interrupts * @ssp: pointer to a struct sifive_serial_port * * Enable interrupt generation when the receive FIFO watermark is reached * on the SiFive UART referred to by @ssp. */ static void __ssp_enable_rxwm(struct sifive_serial_port *ssp) { if (ssp->ier & SIFIVE_SERIAL_IE_RXWM_MASK) return; ssp->ier |= SIFIVE_SERIAL_IE_RXWM_MASK; __ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp); } /** * __ssp_disable_txwm() - disable transmit watermark interrupts * @ssp: pointer to a struct sifive_serial_port * * Disable interrupt generation when the transmit FIFO watermark is reached * on the UART referred to by @ssp. */ static void __ssp_disable_txwm(struct sifive_serial_port *ssp) { if (!(ssp->ier & SIFIVE_SERIAL_IE_TXWM_MASK)) return; ssp->ier &= ~SIFIVE_SERIAL_IE_TXWM_MASK; __ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp); } /** * __ssp_disable_rxwm() - disable receive watermark interrupts * @ssp: pointer to a struct sifive_serial_port * * Disable interrupt generation when the receive FIFO watermark is reached * on the UART referred to by @ssp. */ static void __ssp_disable_rxwm(struct sifive_serial_port *ssp) { if (!(ssp->ier & SIFIVE_SERIAL_IE_RXWM_MASK)) return; ssp->ier &= ~SIFIVE_SERIAL_IE_RXWM_MASK; __ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp); } /** * __ssp_receive_char() - receive a byte from the UART * @ssp: pointer to a struct sifive_serial_port * @is_empty: char pointer to return whether the RX FIFO is empty * * Try to read a byte from the SiFive UART RX FIFO, referenced by * @ssp, and to return it. Also returns the RX FIFO empty bit in * the char pointed to by @ch. The caller must pass the byte back to the * Linux serial layer if needed. * * Returns: the byte read from the UART RX FIFO. */ static char __ssp_receive_char(struct sifive_serial_port *ssp, char *is_empty) { u32 v; u8 ch; v = __ssp_readl(ssp, SIFIVE_SERIAL_RXDATA_OFFS); if (!is_empty) WARN_ON(1); else *is_empty = (v & SIFIVE_SERIAL_RXDATA_EMPTY_MASK) >> SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT; ch = (v & SIFIVE_SERIAL_RXDATA_DATA_MASK) >> SIFIVE_SERIAL_RXDATA_DATA_SHIFT; return ch; } /** * __ssp_receive_chars() - receive multiple bytes from the UART * @ssp: pointer to a struct sifive_serial_port * * Receive up to an RX FIFO's worth of bytes from the SiFive UART referred * to by @ssp and pass them up to the Linux serial layer. * * Context: Expects ssp->port.lock to be held by caller. */ static void __ssp_receive_chars(struct sifive_serial_port *ssp) { unsigned char ch; char is_empty; int c; for (c = SIFIVE_RX_FIFO_DEPTH; c > 0; --c) { ch = __ssp_receive_char(ssp, &is_empty); if (is_empty) break; ssp->port.icount.rx++; uart_insert_char(&ssp->port, 0, 0, ch, TTY_NORMAL); } spin_unlock(&ssp->port.lock); tty_flip_buffer_push(&ssp->port.state->port); spin_lock(&ssp->port.lock); } /** * __ssp_update_div() - calculate the divisor setting by the line rate * @ssp: pointer to a struct sifive_serial_port * * Calculate the appropriate value of the clock divisor for the UART * and target line rate referred to by @ssp and write it into the * hardware. */ static void __ssp_update_div(struct sifive_serial_port *ssp) { u16 div; div = DIV_ROUND_UP(ssp->clkin_rate, ssp->baud_rate) - 1; __ssp_writel(div, SIFIVE_SERIAL_DIV_OFFS, ssp); } /** * __ssp_update_baud_rate() - set the UART "baud rate" * @ssp: pointer to a struct sifive_serial_port * @rate: new target bit rate * * Calculate the UART divisor value for the target bit rate @rate for the * SiFive UART described by @ssp and program it into the UART. There may * be some error between the target bit rate and the actual bit rate implemented * by the UART due to clock ratio granularity. */ static void __ssp_update_baud_rate(struct sifive_serial_port *ssp, unsigned int rate) { if (ssp->baud_rate == rate) return; ssp->baud_rate = rate; __ssp_update_div(ssp); } /** * __ssp_set_stop_bits() - set the number of stop bits * @ssp: pointer to a struct sifive_serial_port * @nstop: 1 or 2 (stop bits) * * Program the SiFive UART referred to by @ssp to use @nstop stop bits. */ static void __ssp_set_stop_bits(struct sifive_serial_port *ssp, char nstop) { u32 v; if (nstop < 1 || nstop > 2) { WARN_ON(1); return; } v = __ssp_readl(ssp, SIFIVE_SERIAL_TXCTRL_OFFS); v &= ~SIFIVE_SERIAL_TXCTRL_NSTOP_MASK; v |= (nstop - 1) << SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT; __ssp_writel(v, SIFIVE_SERIAL_TXCTRL_OFFS, ssp); } /** * __ssp_wait_for_xmitr() - wait for an empty slot on the TX FIFO * @ssp: pointer to a struct sifive_serial_port * * Delay while the UART TX FIFO referred to by @ssp is marked as full. * * Context: Any context. */ static void __maybe_unused __ssp_wait_for_xmitr(struct sifive_serial_port *ssp) { while (sifive_serial_is_txfifo_full(ssp)) udelay(1); /* XXX Could probably be more intelligent here */ } /* * Linux serial API functions */ static void sifive_serial_stop_tx(struct uart_port *port) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); __ssp_disable_txwm(ssp); } static void sifive_serial_stop_rx(struct uart_port *port) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); __ssp_disable_rxwm(ssp); } static void sifive_serial_start_tx(struct uart_port *port) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); __ssp_enable_txwm(ssp); } static irqreturn_t sifive_serial_irq(int irq, void *dev_id) { struct sifive_serial_port *ssp = dev_id; u32 ip; spin_lock(&ssp->port.lock); ip = __ssp_readl(ssp, SIFIVE_SERIAL_IP_OFFS); if (!ip) { spin_unlock(&ssp->port.lock); return IRQ_NONE; } if (ip & SIFIVE_SERIAL_IP_RXWM_MASK) __ssp_receive_chars(ssp); if (ip & SIFIVE_SERIAL_IP_TXWM_MASK) __ssp_transmit_chars(ssp); spin_unlock(&ssp->port.lock); return IRQ_HANDLED; } static unsigned int sifive_serial_tx_empty(struct uart_port *port) { return TIOCSER_TEMT; } static unsigned int sifive_serial_get_mctrl(struct uart_port *port) { return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR; } static void sifive_serial_set_mctrl(struct uart_port *port, unsigned int mctrl) { /* IP block does not support these signals */ } static void sifive_serial_break_ctl(struct uart_port *port, int break_state) { /* IP block does not support sending a break */ } static int sifive_serial_startup(struct uart_port *port) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); __ssp_enable_rxwm(ssp); return 0; } static void sifive_serial_shutdown(struct uart_port *port) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); __ssp_disable_rxwm(ssp); __ssp_disable_txwm(ssp); } /** * sifive_serial_clk_notifier() - clock post-rate-change notifier * @nb: pointer to the struct notifier_block, from the notifier code * @event: event mask from the notifier code * @data: pointer to the struct clk_notifier_data from the notifier code * * On the V0 SoC, the UART IP block is derived from the CPU clock source * after a synchronous divide-by-two divider, so any CPU clock rate change * requires the UART baud rate to be updated. This presumably corrupts any * serial word currently being transmitted or received. In order to avoid * corrupting the output data stream, we drain the transmit queue before * allowing the clock's rate to be changed. */ static int sifive_serial_clk_notifier(struct notifier_block *nb, unsigned long event, void *data) { struct clk_notifier_data *cnd = data; struct sifive_serial_port *ssp = notifier_to_sifive_serial_port(nb); if (event == PRE_RATE_CHANGE) { /* * The TX watermark is always set to 1 by this driver, which * means that the TX busy bit will lower when there are 0 bytes * left in the TX queue -- in other words, when the TX FIFO is * empty. */ __ssp_wait_for_xmitr(ssp); /* * On the cycle the TX FIFO goes empty there is still a full * UART frame left to be transmitted in the shift register. * The UART provides no way for software to directly determine * when that last frame has been transmitted, so we just sleep * here instead. As we're not tracking the number of stop bits * they're just worst cased here. The rest of the serial * framing parameters aren't configurable by software. */ udelay(DIV_ROUND_UP(12 * 1000 * 1000, ssp->baud_rate)); } if (event == POST_RATE_CHANGE && ssp->clkin_rate != cnd->new_rate) { ssp->clkin_rate = cnd->new_rate; __ssp_update_div(ssp); } return NOTIFY_OK; } static void sifive_serial_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); unsigned long flags; u32 v, old_v; int rate; char nstop; if ((termios->c_cflag & CSIZE) != CS8) { dev_err_once(ssp->port.dev, "only 8-bit words supported\n"); termios->c_cflag &= ~CSIZE; termios->c_cflag |= CS8; } if (termios->c_iflag & (INPCK | PARMRK)) dev_err_once(ssp->port.dev, "parity checking not supported\n"); if (termios->c_iflag & BRKINT) dev_err_once(ssp->port.dev, "BREAK detection not supported\n"); termios->c_iflag &= ~(INPCK|PARMRK|BRKINT); /* Set number of stop bits */ nstop = (termios->c_cflag & CSTOPB) ? 2 : 1; __ssp_set_stop_bits(ssp, nstop); /* Set line rate */ rate = uart_get_baud_rate(port, termios, old, 0, ssp->clkin_rate / 16); __ssp_update_baud_rate(ssp, rate); spin_lock_irqsave(&ssp->port.lock, flags); /* Update the per-port timeout */ uart_update_timeout(port, termios->c_cflag, rate); ssp->port.read_status_mask = 0; /* Ignore all characters if CREAD is not set */ v = __ssp_readl(ssp, SIFIVE_SERIAL_RXCTRL_OFFS); old_v = v; if ((termios->c_cflag & CREAD) == 0) v &= SIFIVE_SERIAL_RXCTRL_RXEN_MASK; else v |= SIFIVE_SERIAL_RXCTRL_RXEN_MASK; if (v != old_v) __ssp_writel(v, SIFIVE_SERIAL_RXCTRL_OFFS, ssp); spin_unlock_irqrestore(&ssp->port.lock, flags); } static void sifive_serial_release_port(struct uart_port *port) { } static int sifive_serial_request_port(struct uart_port *port) { return 0; } static void sifive_serial_config_port(struct uart_port *port, int flags) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); ssp->port.type = PORT_SIFIVE_V0; } static int sifive_serial_verify_port(struct uart_port *port, struct serial_struct *ser) { return -EINVAL; } static const char *sifive_serial_type(struct uart_port *port) { return port->type == PORT_SIFIVE_V0 ? "SiFive UART v0" : NULL; } #ifdef CONFIG_CONSOLE_POLL static int sifive_serial_poll_get_char(struct uart_port *port) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); char is_empty, ch; ch = __ssp_receive_char(ssp, &is_empty); if (is_empty) return NO_POLL_CHAR; return ch; } static void sifive_serial_poll_put_char(struct uart_port *port, unsigned char c) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); __ssp_wait_for_xmitr(ssp); __ssp_transmit_char(ssp, c); } #endif /* CONFIG_CONSOLE_POLL */ /* * Early console support */ #ifdef CONFIG_SERIAL_EARLYCON static void early_sifive_serial_putc(struct uart_port *port, int c) { while (__ssp_early_readl(port, SIFIVE_SERIAL_TXDATA_OFFS) & SIFIVE_SERIAL_TXDATA_FULL_MASK) cpu_relax(); __ssp_early_writel(c, SIFIVE_SERIAL_TXDATA_OFFS, port); } static void early_sifive_serial_write(struct console *con, const char *s, unsigned int n) { struct earlycon_device *dev = con->data; struct uart_port *port = &dev->port; uart_console_write(port, s, n, early_sifive_serial_putc); } static int __init early_sifive_serial_setup(struct earlycon_device *dev, const char *options) { struct uart_port *port = &dev->port; if (!port->membase) return -ENODEV; dev->con->write = early_sifive_serial_write; return 0; } OF_EARLYCON_DECLARE(sifive, "sifive,uart0", early_sifive_serial_setup); OF_EARLYCON_DECLARE(sifive, "sifive,fu540-c000-uart0", early_sifive_serial_setup); #endif /* CONFIG_SERIAL_EARLYCON */ /* * Linux console interface */ #ifdef CONFIG_SERIAL_SIFIVE_CONSOLE static struct sifive_serial_port *sifive_serial_console_ports[SIFIVE_SERIAL_MAX_PORTS]; static void sifive_serial_console_putchar(struct uart_port *port, int ch) { struct sifive_serial_port *ssp = port_to_sifive_serial_port(port); __ssp_wait_for_xmitr(ssp); __ssp_transmit_char(ssp, ch); } static void sifive_serial_console_write(struct console *co, const char *s, unsigned int count) { struct sifive_serial_port *ssp = sifive_serial_console_ports[co->index]; unsigned long flags; unsigned int ier; int locked = 1; if (!ssp) return; local_irq_save(flags); if (ssp->port.sysrq) locked = 0; else if (oops_in_progress) locked = spin_trylock(&ssp->port.lock); else spin_lock(&ssp->port.lock); ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS); __ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp); uart_console_write(&ssp->port, s, count, sifive_serial_console_putchar); __ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp); if (locked) spin_unlock(&ssp->port.lock); local_irq_restore(flags); } static int sifive_serial_console_setup(struct console *co, char *options) { struct sifive_serial_port *ssp; int baud = SIFIVE_DEFAULT_BAUD_RATE; int bits = 8; int parity = 'n'; int flow = 'n'; if (co->index < 0 || co->index >= SIFIVE_SERIAL_MAX_PORTS) return -ENODEV; ssp = sifive_serial_console_ports[co->index]; if (!ssp) return -ENODEV; if (options) uart_parse_options(options, &baud, &parity, &bits, &flow); return uart_set_options(&ssp->port, co, baud, parity, bits, flow); } static struct uart_driver sifive_serial_uart_driver; static struct console sifive_serial_console = { .name = SIFIVE_TTY_PREFIX, .write = sifive_serial_console_write, .device = uart_console_device, .setup = sifive_serial_console_setup, .flags = CON_PRINTBUFFER, .index = -1, .data = &sifive_serial_uart_driver, }; static int __init sifive_console_init(void) { register_console(&sifive_serial_console); return 0; } console_initcall(sifive_console_init); static void __ssp_add_console_port(struct sifive_serial_port *ssp) { sifive_serial_console_ports[ssp->port.line] = ssp; } static void __ssp_remove_console_port(struct sifive_serial_port *ssp) { sifive_serial_console_ports[ssp->port.line] = 0; } #define SIFIVE_SERIAL_CONSOLE (&sifive_serial_console) #else #define SIFIVE_SERIAL_CONSOLE NULL static void __ssp_add_console_port(struct sifive_serial_port *ssp) {} static void __ssp_remove_console_port(struct sifive_serial_port *ssp) {} #endif static const struct uart_ops sifive_serial_uops = { .tx_empty = sifive_serial_tx_empty, .set_mctrl = sifive_serial_set_mctrl, .get_mctrl = sifive_serial_get_mctrl, .stop_tx = sifive_serial_stop_tx, .start_tx = sifive_serial_start_tx, .stop_rx = sifive_serial_stop_rx, .break_ctl = sifive_serial_break_ctl, .startup = sifive_serial_startup, .shutdown = sifive_serial_shutdown, .set_termios = sifive_serial_set_termios, .type = sifive_serial_type, .release_port = sifive_serial_release_port, .request_port = sifive_serial_request_port, .config_port = sifive_serial_config_port, .verify_port = sifive_serial_verify_port, #ifdef CONFIG_CONSOLE_POLL .poll_get_char = sifive_serial_poll_get_char, .poll_put_char = sifive_serial_poll_put_char, #endif }; static struct uart_driver sifive_serial_uart_driver = { .owner = THIS_MODULE, .driver_name = SIFIVE_SERIAL_NAME, .dev_name = SIFIVE_TTY_PREFIX, .nr = SIFIVE_SERIAL_MAX_PORTS, .cons = SIFIVE_SERIAL_CONSOLE, }; static int sifive_serial_probe(struct platform_device *pdev) { struct sifive_serial_port *ssp; struct resource *mem; struct clk *clk; void __iomem *base; int irq, id, r; irq = platform_get_irq(pdev, 0); if (irq < 0) return -EPROBE_DEFER; mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); base = devm_ioremap_resource(&pdev->dev, mem); if (IS_ERR(base)) { dev_err(&pdev->dev, "could not acquire device memory\n"); return PTR_ERR(base); } clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(clk)) { dev_err(&pdev->dev, "unable to find controller clock\n"); return PTR_ERR(clk); } id = of_alias_get_id(pdev->dev.of_node, "serial"); if (id < 0) { dev_err(&pdev->dev, "missing aliases entry\n"); return id; } #ifdef CONFIG_SERIAL_SIFIVE_CONSOLE if (id > SIFIVE_SERIAL_MAX_PORTS) { dev_err(&pdev->dev, "too many UARTs (%d)\n", id); return -EINVAL; } #endif ssp = devm_kzalloc(&pdev->dev, sizeof(*ssp), GFP_KERNEL); if (!ssp) return -ENOMEM; ssp->port.dev = &pdev->dev; ssp->port.type = PORT_SIFIVE_V0; ssp->port.iotype = UPIO_MEM; ssp->port.irq = irq; ssp->port.fifosize = SIFIVE_TX_FIFO_DEPTH; ssp->port.ops = &sifive_serial_uops; ssp->port.line = id; ssp->port.mapbase = mem->start; ssp->port.membase = base; ssp->dev = &pdev->dev; ssp->clk = clk; ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier; r = clk_notifier_register(ssp->clk, &ssp->clk_notifier); if (r) { dev_err(&pdev->dev, "could not register clock notifier: %d\n", r); goto probe_out1; } /* Set up clock divider */ ssp->clkin_rate = clk_get_rate(ssp->clk); ssp->baud_rate = SIFIVE_DEFAULT_BAUD_RATE; ssp->port.uartclk = ssp->clkin_rate; __ssp_update_div(ssp); platform_set_drvdata(pdev, ssp); /* Enable transmits and set the watermark level to 1 */ __ssp_writel((1 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT) | SIFIVE_SERIAL_TXCTRL_TXEN_MASK, SIFIVE_SERIAL_TXCTRL_OFFS, ssp); /* Enable receives and set the watermark level to 0 */ __ssp_writel((0 << SIFIVE_SERIAL_RXCTRL_RXCNT_SHIFT) | SIFIVE_SERIAL_RXCTRL_RXEN_MASK, SIFIVE_SERIAL_RXCTRL_OFFS, ssp); r = request_irq(ssp->port.irq, sifive_serial_irq, ssp->port.irqflags, dev_name(&pdev->dev), ssp); if (r) { dev_err(&pdev->dev, "could not attach interrupt: %d\n", r); goto probe_out2; } __ssp_add_console_port(ssp); r = uart_add_one_port(&sifive_serial_uart_driver, &ssp->port); if (r != 0) { dev_err(&pdev->dev, "could not add uart: %d\n", r); goto probe_out3; } return 0; probe_out3: __ssp_remove_console_port(ssp); free_irq(ssp->port.irq, ssp); probe_out2: clk_notifier_unregister(ssp->clk, &ssp->clk_notifier); probe_out1: return r; } static int sifive_serial_remove(struct platform_device *dev) { struct sifive_serial_port *ssp = platform_get_drvdata(dev); __ssp_remove_console_port(ssp); uart_remove_one_port(&sifive_serial_uart_driver, &ssp->port); free_irq(ssp->port.irq, ssp); clk_notifier_unregister(ssp->clk, &ssp->clk_notifier); return 0; } static const struct of_device_id sifive_serial_of_match[] = { { .compatible = "sifive,fu540-c000-uart0" }, { .compatible = "sifive,uart0" }, {}, }; MODULE_DEVICE_TABLE(of, sifive_serial_of_match); static struct platform_driver sifive_serial_platform_driver = { .probe = sifive_serial_probe, .remove = sifive_serial_remove, .driver = { .name = SIFIVE_SERIAL_NAME, .of_match_table = of_match_ptr(sifive_serial_of_match), }, }; static int __init sifive_serial_init(void) { int r; r = uart_register_driver(&sifive_serial_uart_driver); if (r) goto init_out1; r = platform_driver_register(&sifive_serial_platform_driver); if (r) goto init_out2; return 0; init_out2: uart_unregister_driver(&sifive_serial_uart_driver); init_out1: return r; } static void __exit sifive_serial_exit(void) { platform_driver_unregister(&sifive_serial_platform_driver); uart_unregister_driver(&sifive_serial_uart_driver); } module_init(sifive_serial_init); module_exit(sifive_serial_exit); MODULE_DESCRIPTION("SiFive UART serial driver"); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul Walmsley ");