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Diffstat (limited to 'drivers/tty/serial/sifive.c')
| -rw-r--r-- | drivers/tty/serial/sifive.c | 1056 |
1 files changed, 1056 insertions, 0 deletions
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c new file mode 100644 index 000000000000..be4687814353 --- /dev/null +++ b/drivers/tty/serial/sifive.c @@ -0,0 +1,1056 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * SiFive UART driver + * Copyright (C) 2018 Paul Walmsley <paul@pwsan.com> + * 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 <linux/clk.h> +#include <linux/console.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/irq.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_irq.h> +#include <linux/platform_device.h> +#include <linux/serial_core.h> +#include <linux/serial_reg.h> +#include <linux/slab.h> +#include <linux/tty.h> +#include <linux/tty_flip.h> + +/* + * 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 could corrupt any + * serial word currently being transmitted or received. It would probably + * be better to stop receives and transmits, then complete the baud rate + * change, then re-enable them. + */ +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 == 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"); + 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"); + + /* 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; +} + +/* + * 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 __init 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, +}; + +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) { + dev_err(&pdev->dev, "could not acquire interrupt\n"); + 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_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 <paul@pwsan.com>"); |