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// SPDX-License-Identifier: GPL-2.0+
/* Synopsys DesignWare 8250 library. */
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/serial_8250.h>
#include <linux/serial_core.h>
#include "8250_dwlib.h"
/* Offsets for the DesignWare specific registers */
#define DW_UART_DLF 0xc0 /* Divisor Latch Fraction Register */
#define DW_UART_CPR 0xf4 /* Component Parameter Register */
#define DW_UART_UCV 0xf8 /* UART Component Version */
/* Component Parameter Register bits */
#define DW_UART_CPR_ABP_DATA_WIDTH (3 << 0)
#define DW_UART_CPR_AFCE_MODE (1 << 4)
#define DW_UART_CPR_THRE_MODE (1 << 5)
#define DW_UART_CPR_SIR_MODE (1 << 6)
#define DW_UART_CPR_SIR_LP_MODE (1 << 7)
#define DW_UART_CPR_ADDITIONAL_FEATURES (1 << 8)
#define DW_UART_CPR_FIFO_ACCESS (1 << 9)
#define DW_UART_CPR_FIFO_STAT (1 << 10)
#define DW_UART_CPR_SHADOW (1 << 11)
#define DW_UART_CPR_ENCODED_PARMS (1 << 12)
#define DW_UART_CPR_DMA_EXTRA (1 << 13)
#define DW_UART_CPR_FIFO_MODE (0xff << 16)
/* Helper for FIFO size calculation */
#define DW_UART_CPR_FIFO_SIZE(a) (((a >> 16) & 0xff) * 16)
static inline u32 dw8250_readl_ext(struct uart_port *p, int offset)
{
if (p->iotype == UPIO_MEM32BE)
return ioread32be(p->membase + offset);
return readl(p->membase + offset);
}
static inline void dw8250_writel_ext(struct uart_port *p, int offset, u32 reg)
{
if (p->iotype == UPIO_MEM32BE)
iowrite32be(reg, p->membase + offset);
else
writel(reg, p->membase + offset);
}
/*
* 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_setup_port(struct uart_port *p)
{
struct uart_8250_port *up = up_to_u8250p(p);
u32 reg, old_dlf;
/*
* 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) {
struct dw8250_port_data *d = p->private_data;
d->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)
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;
}
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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