205 lines
4.7 KiB
C
205 lines
4.7 KiB
C
/*
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* based on linux.git/drivers/tty/serial/serial_ar933x.c
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <common.h>
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#include <driver.h>
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#include <init.h>
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#include <malloc.h>
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#include <io.h>
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#include <asm-generic/div64.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include "serial_ar933x.h"
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#define AR933X_UART_MAX_SCALE 0xff
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#define AR933X_UART_MAX_STEP 0xffff
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struct ar933x_uart_priv {
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void __iomem *base;
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struct clk *clk;
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};
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static inline void ar933x_serial_writel(struct console_device *cdev,
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u32 b, int offset)
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{
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struct ar933x_uart_priv *priv = cdev->dev->priv;
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cpu_writel(b, priv->base + offset);
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}
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static inline u32 ar933x_serial_readl(struct console_device *cdev,
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int offset)
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{
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struct ar933x_uart_priv *priv = cdev->dev->priv;
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return cpu_readl(priv->base + offset);
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}
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/*
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* baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
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* take from linux.
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*/
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static unsigned long ar933x_uart_get_baud(unsigned int clk,
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unsigned int scale,
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unsigned int step)
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{
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u64 t;
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u32 div;
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div = (2 << 16) * (scale + 1);
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t = clk;
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t *= step;
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t += (div / 2);
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do_div(t, div);
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return t;
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}
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static void ar933x_uart_get_scale_step(unsigned int clk,
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unsigned int baud,
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unsigned int *scale,
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unsigned int *step)
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{
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unsigned int tscale;
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long min_diff;
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*scale = 0;
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*step = 0;
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min_diff = baud;
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for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
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u64 tstep;
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int diff;
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tstep = baud * (tscale + 1);
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tstep *= (2 << 16);
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do_div(tstep, clk);
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if (tstep > AR933X_UART_MAX_STEP)
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break;
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diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
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if (diff < min_diff) {
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min_diff = diff;
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*scale = tscale;
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*step = tstep;
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}
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}
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}
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static int ar933x_serial_setbaudrate(struct console_device *cdev, int baudrate)
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{
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struct ar933x_uart_priv *priv = cdev->dev->priv;
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unsigned int scale, step;
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ar933x_uart_get_scale_step(clk_get_rate(priv->clk), baudrate, &scale,
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&step);
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ar933x_serial_writel(cdev, (scale << AR933X_UART_CLOCK_SCALE_S) | step,
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AR933X_UART_CLOCK_REG);
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return 0;
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}
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static void ar933x_serial_putc(struct console_device *cdev, char ch)
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{
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u32 data;
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/* wait transmitter ready */
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data = ar933x_serial_readl(cdev, AR933X_UART_DATA_REG);
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while (!(data & AR933X_UART_DATA_TX_CSR))
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data = ar933x_serial_readl(cdev, AR933X_UART_DATA_REG);
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data = (ch & AR933X_UART_DATA_TX_RX_MASK) | AR933X_UART_DATA_TX_CSR;
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ar933x_serial_writel(cdev, data, AR933X_UART_DATA_REG);
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}
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static int ar933x_serial_tstc(struct console_device *cdev)
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{
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u32 rdata;
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rdata = ar933x_serial_readl(cdev, AR933X_UART_DATA_REG);
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return rdata & AR933X_UART_DATA_RX_CSR;
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}
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static int ar933x_serial_getc(struct console_device *cdev)
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{
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u32 rdata;
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while (!ar933x_serial_tstc(cdev))
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;
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rdata = ar933x_serial_readl(cdev, AR933X_UART_DATA_REG);
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/* remove the character from the FIFO */
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ar933x_serial_writel(cdev, AR933X_UART_DATA_RX_CSR,
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AR933X_UART_DATA_REG);
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return rdata & AR933X_UART_DATA_TX_RX_MASK;
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}
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static int ar933x_serial_probe(struct device_d *dev)
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{
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struct console_device *cdev;
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struct ar933x_uart_priv *priv;
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u32 uart_cs;
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cdev = xzalloc(sizeof(struct console_device));
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priv = xzalloc(sizeof(struct ar933x_uart_priv));
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priv->base = dev_request_mem_region(dev, 0);
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dev->priv = priv;
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cdev->dev = dev;
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cdev->tstc = ar933x_serial_tstc;
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cdev->putc = ar933x_serial_putc;
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cdev->getc = ar933x_serial_getc;
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cdev->setbrg = ar933x_serial_setbaudrate;
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priv->clk = clk_get(dev, NULL);
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if (IS_ERR(priv->clk)) {
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dev_err(dev, "unable to get UART clock\n");
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return PTR_ERR(priv->clk);
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}
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uart_cs = (AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S)
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| AR933X_UART_CS_TX_READY_ORIDE
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| AR933X_UART_CS_RX_READY_ORIDE;
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ar933x_serial_writel(cdev, uart_cs, AR933X_UART_CS_REG);
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/* FIXME: need ar933x_serial_init_port(cdev); */
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console_register(cdev);
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return 0;
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}
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static struct of_device_id ar933x_serial_dt_ids[] = {
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{
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.compatible = "qca,ar9330-uart",
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}, {
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/* sentinel */
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},
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};
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static struct driver_d ar933x_serial_driver = {
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.name = "ar933x_serial",
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.probe = ar933x_serial_probe,
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.of_compatible = DRV_OF_COMPAT(ar933x_serial_dt_ids),
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};
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console_platform_driver(ar933x_serial_driver);
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