127 lines
3.5 KiB
C
127 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/* Synopsys DesignWare 8250 library. */
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#include <linux/bitops.h>
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#include <linux/device.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/serial_8250.h>
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#include <linux/serial_core.h>
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#include "8250_dwlib.h"
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/* Offsets for the DesignWare specific registers */
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#define DW_UART_DLF 0xc0 /* Divisor Latch Fraction Register */
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#define DW_UART_CPR 0xf4 /* Component Parameter Register */
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#define DW_UART_UCV 0xf8 /* UART Component Version */
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/* Component Parameter Register bits */
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#define DW_UART_CPR_ABP_DATA_WIDTH (3 << 0)
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#define DW_UART_CPR_AFCE_MODE (1 << 4)
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#define DW_UART_CPR_THRE_MODE (1 << 5)
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#define DW_UART_CPR_SIR_MODE (1 << 6)
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#define DW_UART_CPR_SIR_LP_MODE (1 << 7)
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#define DW_UART_CPR_ADDITIONAL_FEATURES (1 << 8)
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#define DW_UART_CPR_FIFO_ACCESS (1 << 9)
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#define DW_UART_CPR_FIFO_STAT (1 << 10)
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#define DW_UART_CPR_SHADOW (1 << 11)
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#define DW_UART_CPR_ENCODED_PARMS (1 << 12)
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#define DW_UART_CPR_DMA_EXTRA (1 << 13)
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#define DW_UART_CPR_FIFO_MODE (0xff << 16)
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/* Helper for FIFO size calculation */
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#define DW_UART_CPR_FIFO_SIZE(a) (((a >> 16) & 0xff) * 16)
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static inline u32 dw8250_readl_ext(struct uart_port *p, int offset)
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{
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if (p->iotype == UPIO_MEM32BE)
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return ioread32be(p->membase + offset);
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return readl(p->membase + offset);
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}
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static inline void dw8250_writel_ext(struct uart_port *p, int offset, u32 reg)
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{
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if (p->iotype == UPIO_MEM32BE)
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iowrite32be(reg, p->membase + offset);
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else
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writel(reg, p->membase + offset);
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}
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/*
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* divisor = div(I) + div(F)
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* "I" means integer, "F" means fractional
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* quot = div(I) = clk / (16 * baud)
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* frac = div(F) * 2^dlf_size
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*
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* let rem = clk % (16 * baud)
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* we have: div(F) * (16 * baud) = rem
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* so frac = 2^dlf_size * rem / (16 * baud) = (rem << dlf_size) / (16 * baud)
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*/
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static unsigned int dw8250_get_divisor(struct uart_port *p, unsigned int baud,
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unsigned int *frac)
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{
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unsigned int quot, rem, base_baud = baud * 16;
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struct dw8250_port_data *d = p->private_data;
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quot = p->uartclk / base_baud;
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rem = p->uartclk % base_baud;
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*frac = DIV_ROUND_CLOSEST(rem << d->dlf_size, base_baud);
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return quot;
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}
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static void dw8250_set_divisor(struct uart_port *p, unsigned int baud,
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unsigned int quot, unsigned int quot_frac)
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{
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dw8250_writel_ext(p, DW_UART_DLF, quot_frac);
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serial8250_do_set_divisor(p, baud, quot, quot_frac);
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}
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void dw8250_setup_port(struct uart_port *p)
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{
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struct uart_8250_port *up = up_to_u8250p(p);
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u32 reg;
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/*
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* If the Component Version Register returns zero, we know that
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* ADDITIONAL_FEATURES are not enabled. No need to go any further.
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*/
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reg = dw8250_readl_ext(p, DW_UART_UCV);
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if (!reg)
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return;
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dev_dbg(p->dev, "Designware UART version %c.%c%c\n",
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(reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff);
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dw8250_writel_ext(p, DW_UART_DLF, ~0U);
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reg = dw8250_readl_ext(p, DW_UART_DLF);
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dw8250_writel_ext(p, DW_UART_DLF, 0);
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if (reg) {
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struct dw8250_port_data *d = p->private_data;
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d->dlf_size = fls(reg);
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p->get_divisor = dw8250_get_divisor;
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p->set_divisor = dw8250_set_divisor;
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}
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reg = dw8250_readl_ext(p, DW_UART_CPR);
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if (!reg)
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return;
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/* Select the type based on FIFO */
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if (reg & DW_UART_CPR_FIFO_MODE) {
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p->type = PORT_16550A;
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p->flags |= UPF_FIXED_TYPE;
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p->fifosize = DW_UART_CPR_FIFO_SIZE(reg);
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up->capabilities = UART_CAP_FIFO;
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}
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if (reg & DW_UART_CPR_AFCE_MODE)
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up->capabilities |= UART_CAP_AFE;
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if (reg & DW_UART_CPR_SIR_MODE)
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up->capabilities |= UART_CAP_IRDA;
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}
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EXPORT_SYMBOL_GPL(dw8250_setup_port);
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