target/linux/rtl838x/files-5.4/arch/mips/rtl838x/serial.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * 8250 serial console setup for the Realtek RTL838X SoC
   4  *
   5  * based on the original BSP by
   6  * Copyright (C) 2006-2012 Tony Wu (tonywu@realtek.com)
   7  *
   8  * Copyright (C) 2020 B. Koblitz
   9  *
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/ctype.h>
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/version.h>
  17 #include <linux/serial.h>
  18 #include <linux/serial_core.h>
  19 #include <linux/serial_8250.h>
  20 #include <linux/serial_reg.h>
  21 #include <linux/tty.h>
  22 #include <linux/clk.h>
  23
  24 #include <asm/mach-rtl838x/mach-rtl838x.h>
  25
  26 extern char arcs_cmdline[];
  27
  28 int __init rtl838x_serial_init(void)
  29 {
  30 #ifdef CONFIG_SERIAL_8250
  31         int ret;
  32         struct uart_port p;
  33         unsigned long baud = 0;
  34         int err;
  35         char parity = '\0', bits = '\0', flow = '\0';
  36         char *s;
  37         struct device_node *dn;
  38
  39         dn = of_find_compatible_node(NULL, NULL, "ns16550a");
  40         if (dn) {
  41                 pr_info("Found NS16550a: %s (%s)\n", dn->name, dn->full_name);
  42                 dn = of_find_compatible_node(dn, NULL, "ns16550a");
  43                 if (dn && of_device_is_available(dn) && soc_info.family == RTL8380_FAMILY_ID) {
  44                         /* Enable UART1 on RTL838x */
  45                         pr_info("Enabling uart1\n");
  46                         sw_w32(0x10, RTL838X_GMII_INTF_SEL);
  47                 }
  48         } else {
  49                 pr_err("No NS16550a UART found!");
  50                 return -ENODEV;
  51         }
  52
  53         s = strstr(arcs_cmdline, "console=ttyS0,");
  54         if (s) {
  55                 s += 14;
  56                 err = kstrtoul(s, 10, &baud);
  57                 if (err)
  58                         baud = 0;
  59                 while (isdigit(*s))
  60                         s++;
  61                 if (*s == ',')
  62                         s++;
  63                 if (*s)
  64                         parity = *s++;
  65                 if (*s == ',')
  66                         s++;
  67                 if (*s)
  68                         bits = *s++;
  69                 if (*s == ',')
  70                         s++;
  71                 if (*s == 'h')
  72                         flow = 'r';
  73         }
  74
  75         if (baud == 0) {
  76                 baud = 38400;
  77                 pr_warn("Using default baud rate: %lu\n", baud);
  78         }
  79         if (parity != 'n' && parity != 'o' && parity != 'e')
  80                 parity = 'n';
  81         if (bits != '7' && bits != '8')
  82                 bits = '8';
  83
  84         memset(&p, 0, sizeof(p));
  85
  86         p.type = PORT_16550A;
  87         p.membase = (unsigned char *) RTL838X_UART0_BASE;
  88         p.irq = RTL838X_UART0_IRQ;
  89         p.uartclk = SYSTEM_FREQ - (24 * baud);
  90         p.flags = UPF_SKIP_TEST | UPF_LOW_LATENCY | UPF_FIXED_TYPE;
  91         p.iotype = UPIO_MEM;
  92         p.regshift = 2;
  93         p.fifosize = 1;
  94
  95         /* Call early_serial_setup() here, to set up 8250 console driver */
  96         if (early_serial_setup(&p) != 0)
  97                 ret = 1;
  98 #endif
  99         return 0;
 100 }