arch/arm/mach-davinci/serial.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * TI DaVinci serial driver
   4  *
   5  * Copyright (C) 2006 Texas Instruments.
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/init.h>
  10 #include <linux/serial_8250.h>
  11 #include <linux/serial_reg.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/delay.h>
  14 #include <linux/clk.h>
  15 #include <linux/io.h>
  16
  17 #include <mach/serial.h>
  18 #include <mach/cputype.h>
  19
  20 static inline void serial_write_reg(struct plat_serial8250_port *p, int offset,
  21                                     int value)
  22 {
  23         offset <<= p->regshift;
  24
  25         WARN_ONCE(!p->membase, "unmapped write: uart[%d]\n", offset);
  26
  27         __raw_writel(value, p->membase + offset);
  28 }
  29
  30 static void __init davinci_serial_reset(struct plat_serial8250_port *p)
  31 {
  32         unsigned int pwremu = 0;
  33
  34         serial_write_reg(p, UART_IER, 0);  /* disable all interrupts */
  35
  36         /* reset both transmitter and receiver: bits 14,13 = UTRST, URRST */
  37         serial_write_reg(p, UART_DAVINCI_PWREMU, pwremu);
  38         mdelay(10);
  39
  40         pwremu |= (0x3 << 13);
  41         pwremu |= 0x1;
  42         serial_write_reg(p, UART_DAVINCI_PWREMU, pwremu);
  43
  44         if (cpu_is_davinci_dm646x())
  45                 serial_write_reg(p, UART_DM646X_SCR,
  46                                  UART_DM646X_SCR_TX_WATERMARK);
  47 }
  48
  49 int __init davinci_serial_init(struct platform_device *serial_dev)
  50 {
  51         int i, ret = 0;
  52         struct device *dev;
  53         struct plat_serial8250_port *p;
  54         struct clk *clk;
  55
  56         /*
  57          * Make sure the serial ports are muxed on at this point.
  58          * You have to mux them off in device drivers later on if not needed.
  59          */
  60         for (i = 0; serial_dev[i].dev.platform_data != NULL; i++) {
  61                 dev = &serial_dev[i].dev;
  62                 p = dev->platform_data;
  63
  64                 ret = platform_device_register(&serial_dev[i]);
  65                 if (ret)
  66                         continue;
  67
  68                 clk = clk_get(dev, NULL);
  69                 if (IS_ERR(clk)) {
  70                         pr_err("%s:%d: failed to get UART%d clock\n",
  71                                __func__, __LINE__, i);
  72                         continue;
  73                 }
  74
  75                 clk_prepare_enable(clk);
  76
  77                 p->uartclk = clk_get_rate(clk);
  78
  79                 if (!p->membase && p->mapbase) {
  80                         p->membase = ioremap(p->mapbase, SZ_4K);
  81
  82                         if (p->membase)
  83                                 p->flags &= ~UPF_IOREMAP;
  84                         else
  85                                 pr_err("uart regs ioremap failed\n");
  86                 }
  87
  88                 if (p->membase && p->type != PORT_AR7)
  89                         davinci_serial_reset(p);
  90         }
  91         return ret;
  92 }