diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/tty/serial/8250/8250_dwlib.c | 307 |
1 files changed, 307 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_dwlib.c b/drivers/tty/serial/8250/8250_dwlib.c new file mode 100644 index 000000000..84843e204 --- /dev/null +++ b/drivers/tty/serial/8250/8250_dwlib.c @@ -0,0 +1,307 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* Synopsys DesignWare 8250 library. */ + +#include <linux/bitops.h> +#include <linux/bitfield.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/math.h> +#include <linux/property.h> +#include <linux/serial_8250.h> +#include <linux/serial_core.h> + +#include "8250_dwlib.h" + +/* Offsets for the DesignWare specific registers */ +#define DW_UART_TCR 0xac /* Transceiver Control Register (RS485) */ +#define DW_UART_DE_EN 0xb0 /* Driver Output Enable Register */ +#define DW_UART_RE_EN 0xb4 /* Receiver Output Enable Register */ +#define DW_UART_DLF 0xc0 /* Divisor Latch Fraction Register */ +#define DW_UART_RAR 0xc4 /* Receive Address Register */ +#define DW_UART_TAR 0xc8 /* Transmit Address Register */ +#define DW_UART_LCR_EXT 0xcc /* Line Extended Control Register */ +#define DW_UART_CPR 0xf4 /* Component Parameter Register */ +#define DW_UART_UCV 0xf8 /* UART Component Version */ + +/* Receive / Transmit Address Register bits */ +#define DW_UART_ADDR_MASK GENMASK(7, 0) + +/* Line Status Register bits */ +#define DW_UART_LSR_ADDR_RCVD BIT(8) + +/* Transceiver Control Register bits */ +#define DW_UART_TCR_RS485_EN BIT(0) +#define DW_UART_TCR_RE_POL BIT(1) +#define DW_UART_TCR_DE_POL BIT(2) +#define DW_UART_TCR_XFER_MODE GENMASK(4, 3) +#define DW_UART_TCR_XFER_MODE_DE_DURING_RE FIELD_PREP(DW_UART_TCR_XFER_MODE, 0) +#define DW_UART_TCR_XFER_MODE_SW_DE_OR_RE FIELD_PREP(DW_UART_TCR_XFER_MODE, 1) +#define DW_UART_TCR_XFER_MODE_DE_OR_RE FIELD_PREP(DW_UART_TCR_XFER_MODE, 2) + +/* Line Extended Control Register bits */ +#define DW_UART_LCR_EXT_DLS_E BIT(0) +#define DW_UART_LCR_EXT_ADDR_MATCH BIT(1) +#define DW_UART_LCR_EXT_SEND_ADDR BIT(2) +#define DW_UART_LCR_EXT_TRANSMIT_MODE BIT(3) + +/* Component Parameter Register bits */ +#define DW_UART_CPR_ABP_DATA_WIDTH GENMASK(1, 0) +#define DW_UART_CPR_AFCE_MODE BIT(4) +#define DW_UART_CPR_THRE_MODE BIT(5) +#define DW_UART_CPR_SIR_MODE BIT(6) +#define DW_UART_CPR_SIR_LP_MODE BIT(7) +#define DW_UART_CPR_ADDITIONAL_FEATURES BIT(8) +#define DW_UART_CPR_FIFO_ACCESS BIT(9) +#define DW_UART_CPR_FIFO_STAT BIT(10) +#define DW_UART_CPR_SHADOW BIT(11) +#define DW_UART_CPR_ENCODED_PARMS BIT(12) +#define DW_UART_CPR_DMA_EXTRA BIT(13) +#define DW_UART_CPR_FIFO_MODE GENMASK(23, 16) + +/* Helper for FIFO size calculation */ +#define DW_UART_CPR_FIFO_SIZE(a) (FIELD_GET(DW_UART_CPR_FIFO_MODE, (a)) * 16) + +/* + * divisor = div(I) + div(F) + * "I" means integer, "F" means fractional + * quot = div(I) = clk / (16 * baud) + * frac = div(F) * 2^dlf_size + * + * let rem = clk % (16 * baud) + * we have: div(F) * (16 * baud) = rem + * so frac = 2^dlf_size * rem / (16 * baud) = (rem << dlf_size) / (16 * baud) + */ +static unsigned int dw8250_get_divisor(struct uart_port *p, unsigned int baud, + unsigned int *frac) +{ + unsigned int quot, rem, base_baud = baud * 16; + struct dw8250_port_data *d = p->private_data; + + quot = p->uartclk / base_baud; + rem = p->uartclk % base_baud; + *frac = DIV_ROUND_CLOSEST(rem << d->dlf_size, base_baud); + + return quot; +} + +static void dw8250_set_divisor(struct uart_port *p, unsigned int baud, + unsigned int quot, unsigned int quot_frac) +{ + dw8250_writel_ext(p, DW_UART_DLF, quot_frac); + serial8250_do_set_divisor(p, baud, quot, quot_frac); +} + +void dw8250_do_set_termios(struct uart_port *p, struct ktermios *termios, + const struct ktermios *old) +{ + p->status &= ~UPSTAT_AUTOCTS; + if (termios->c_cflag & CRTSCTS) + p->status |= UPSTAT_AUTOCTS; + + serial8250_do_set_termios(p, termios, old); + + /* Filter addresses which have 9th bit set */ + p->ignore_status_mask |= DW_UART_LSR_ADDR_RCVD; + p->read_status_mask |= DW_UART_LSR_ADDR_RCVD; +} +EXPORT_SYMBOL_GPL(dw8250_do_set_termios); + +/* + * Wait until re is de-asserted for sure. An ongoing receive will keep + * re asserted until end of frame. Without BUSY indication available, + * only available course of action is to wait for the time it takes to + * receive one frame (there might nothing to receive but w/o BUSY the + * driver cannot know). + */ +static void dw8250_wait_re_deassert(struct uart_port *p) +{ + ndelay(p->frame_time); +} + +static void dw8250_update_rar(struct uart_port *p, u32 addr) +{ + u32 re_en = dw8250_readl_ext(p, DW_UART_RE_EN); + + /* + * RAR shouldn't be changed while receiving. Thus, de-assert RE_EN + * if asserted and wait. + */ + if (re_en) + dw8250_writel_ext(p, DW_UART_RE_EN, 0); + dw8250_wait_re_deassert(p); + dw8250_writel_ext(p, DW_UART_RAR, addr); + if (re_en) + dw8250_writel_ext(p, DW_UART_RE_EN, re_en); +} + +static void dw8250_rs485_set_addr(struct uart_port *p, struct serial_rs485 *rs485, + struct ktermios *termios) +{ + u32 lcr = dw8250_readl_ext(p, DW_UART_LCR_EXT); + + if (rs485->flags & SER_RS485_ADDRB) { + lcr |= DW_UART_LCR_EXT_DLS_E; + if (termios) + termios->c_cflag |= ADDRB; + + if (rs485->flags & SER_RS485_ADDR_RECV) { + u32 delta = p->rs485.flags ^ rs485->flags; + + /* + * rs485 (param) is equal to uart_port's rs485 only during init + * (during init, delta is not yet applicable). + */ + if (unlikely(&p->rs485 == rs485)) + delta = rs485->flags; + + if ((delta & SER_RS485_ADDR_RECV) || + (p->rs485.addr_recv != rs485->addr_recv)) + dw8250_update_rar(p, rs485->addr_recv); + lcr |= DW_UART_LCR_EXT_ADDR_MATCH; + } else { + lcr &= ~DW_UART_LCR_EXT_ADDR_MATCH; + } + if (rs485->flags & SER_RS485_ADDR_DEST) { + /* + * Don't skip writes here as another endpoint could + * have changed communication line's destination + * address in between. + */ + dw8250_writel_ext(p, DW_UART_TAR, rs485->addr_dest); + lcr |= DW_UART_LCR_EXT_SEND_ADDR; + } + } else { + lcr = 0; + } + dw8250_writel_ext(p, DW_UART_LCR_EXT, lcr); +} + +static int dw8250_rs485_config(struct uart_port *p, struct ktermios *termios, + struct serial_rs485 *rs485) +{ + u32 tcr; + + tcr = dw8250_readl_ext(p, DW_UART_TCR); + tcr &= ~DW_UART_TCR_XFER_MODE; + + if (rs485->flags & SER_RS485_ENABLED) { + tcr |= DW_UART_TCR_RS485_EN; + + if (rs485->flags & SER_RS485_RX_DURING_TX) + tcr |= DW_UART_TCR_XFER_MODE_DE_DURING_RE; + else + tcr |= DW_UART_TCR_XFER_MODE_DE_OR_RE; + dw8250_writel_ext(p, DW_UART_DE_EN, 1); + dw8250_writel_ext(p, DW_UART_RE_EN, 1); + } else { + if (termios) + termios->c_cflag &= ~ADDRB; + + tcr &= ~DW_UART_TCR_RS485_EN; + } + + /* Reset to default polarity */ + tcr |= DW_UART_TCR_DE_POL; + tcr &= ~DW_UART_TCR_RE_POL; + + if (!(rs485->flags & SER_RS485_RTS_ON_SEND)) + tcr &= ~DW_UART_TCR_DE_POL; + if (device_property_read_bool(p->dev, "rs485-rx-active-high")) + tcr |= DW_UART_TCR_RE_POL; + + dw8250_writel_ext(p, DW_UART_TCR, tcr); + + /* Addressing mode can only be set up after TCR */ + if (rs485->flags & SER_RS485_ENABLED) + dw8250_rs485_set_addr(p, rs485, termios); + + return 0; +} + +/* + * Tests if RE_EN register can have non-zero value to see if RS-485 HW support + * is present. + */ +static bool dw8250_detect_rs485_hw(struct uart_port *p) +{ + u32 reg; + + dw8250_writel_ext(p, DW_UART_RE_EN, 1); + reg = dw8250_readl_ext(p, DW_UART_RE_EN); + dw8250_writel_ext(p, DW_UART_RE_EN, 0); + return reg; +} + +static const struct serial_rs485 dw8250_rs485_supported = { + .flags = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX | SER_RS485_RTS_ON_SEND | + SER_RS485_RTS_AFTER_SEND | SER_RS485_ADDRB | SER_RS485_ADDR_RECV | + SER_RS485_ADDR_DEST, +}; + +void dw8250_setup_port(struct uart_port *p) +{ + struct dw8250_port_data *pd = p->private_data; + struct dw8250_data *data = to_dw8250_data(pd); + struct uart_8250_port *up = up_to_u8250p(p); + u32 reg, old_dlf; + + pd->hw_rs485_support = dw8250_detect_rs485_hw(p); + if (pd->hw_rs485_support) { + p->rs485_config = dw8250_rs485_config; + up->lsr_save_mask = LSR_SAVE_FLAGS | DW_UART_LSR_ADDR_RCVD; + p->rs485_supported = dw8250_rs485_supported; + } else { + p->rs485_config = serial8250_em485_config; + p->rs485_supported = serial8250_em485_supported; + up->rs485_start_tx = serial8250_em485_start_tx; + up->rs485_stop_tx = serial8250_em485_stop_tx; + } + up->capabilities |= UART_CAP_NOTEMT; + + /* + * If the Component Version Register returns zero, we know that + * ADDITIONAL_FEATURES are not enabled. No need to go any further. + */ + reg = dw8250_readl_ext(p, DW_UART_UCV); + if (!reg) + return; + + dev_dbg(p->dev, "Designware UART version %c.%c%c\n", + (reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff); + + /* Preserve value written by firmware or bootloader */ + old_dlf = dw8250_readl_ext(p, DW_UART_DLF); + dw8250_writel_ext(p, DW_UART_DLF, ~0U); + reg = dw8250_readl_ext(p, DW_UART_DLF); + dw8250_writel_ext(p, DW_UART_DLF, old_dlf); + + if (reg) { + pd->dlf_size = fls(reg); + p->get_divisor = dw8250_get_divisor; + p->set_divisor = dw8250_set_divisor; + } + + reg = dw8250_readl_ext(p, DW_UART_CPR); + if (!reg) { + reg = data->pdata->cpr_val; + dev_dbg(p->dev, "CPR is not available, using 0x%08x instead\n", reg); + } + if (!reg) + return; + + /* Select the type based on FIFO */ + if (reg & DW_UART_CPR_FIFO_MODE) { + p->type = PORT_16550A; + p->flags |= UPF_FIXED_TYPE; + p->fifosize = DW_UART_CPR_FIFO_SIZE(reg); + up->capabilities = UART_CAP_FIFO | UART_CAP_NOTEMT; + } + + if (reg & DW_UART_CPR_AFCE_MODE) + up->capabilities |= UART_CAP_AFE; + + if (reg & DW_UART_CPR_SIR_MODE) + up->capabilities |= UART_CAP_IRDA; +} +EXPORT_SYMBOL_GPL(dw8250_setup_port); |