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// 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, 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;
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);
dw8250_writel_ext(p, DW_UART_DLF, ~0U);
reg = dw8250_readl_ext(p, DW_UART_DLF);
dw8250_writel_ext(p, DW_UART_DLF, 0);
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);
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