arch/powerpc/platforms/embedded6xx/ls_uart.c

   1 /*
   2  * AVR power-management chip interface for the Buffalo Linkstation /
   3  * Kurobox Platform.
   4  *
   5  * Author: 2006 (c) G. Liakhovetski
   6  *       g.liakhovetski@gmx.de
   7  *
   8  * This file is licensed under the terms of the GNU General Public License
   9  * version 2.  This program is licensed "as is" without any warranty of
  10  * any kind, whether express or implied.
  11  */
  12 #include <linux/workqueue.h>
  13 #include <linux/string.h>
  14 #include <linux/delay.h>
  15 #include <linux/serial_reg.h>
  16 #include <linux/serial_8250.h>
  17 #include <asm/io.h>
  18 #include <asm/prom.h>
  19 #include <asm/termbits.h>
  20
  21 #include "mpc10x.h"
  22
  23 static void __iomem *avr_addr;
  24 static unsigned long avr_clock;
  25
  26 static struct work_struct wd_work;
  27
  28 static void wd_stop(struct work_struct *unused)
  29 {
  30         const char string[] = "AAAAFFFFJJJJ>>>>VVVV>>>>ZZZZVVVVKKKK";
  31         int i = 0, rescue = 8;
  32         int len = strlen(string);
  33
  34         while (rescue--) {
  35                 int j;
  36                 char lsr = in_8(avr_addr + UART_LSR);
  37
  38                 if (lsr & (UART_LSR_THRE | UART_LSR_TEMT)) {
  39                         for (j = 0; j < 16 && i < len; j++, i++)
  40                                 out_8(avr_addr + UART_TX, string[i]);
  41                         if (i == len) {
  42                                 /* Read "OK" back: 4ms for the last "KKKK"
  43                                    plus a couple bytes back */
  44                                 msleep(7);
  45                                 printk("linkstation: disarming the AVR watchdog: ");
  46                                 while (in_8(avr_addr + UART_LSR) & UART_LSR_DR)
  47                                         printk("%c", in_8(avr_addr + UART_RX));
  48                                 break;
  49                         }
  50                 }
  51                 msleep(17);
  52         }
  53         printk("\n");
  54 }
  55
  56 #define AVR_QUOT(clock) ((clock) + 8 * 9600) / (16 * 9600)
  57
  58 void avr_uart_configure(void)
  59 {
  60         unsigned char cval = UART_LCR_WLEN8;
  61         unsigned int quot = AVR_QUOT(avr_clock);
  62
  63         if (!avr_addr || !avr_clock)
  64                 return;
  65
  66         out_8(avr_addr + UART_LCR, cval);                       /* initialise UART */
  67         out_8(avr_addr + UART_MCR, 0);
  68         out_8(avr_addr + UART_IER, 0);
  69
  70         cval |= UART_LCR_STOP | UART_LCR_PARITY | UART_LCR_EPAR;
  71
  72         out_8(avr_addr + UART_LCR, cval);                       /* Set character format */
  73
  74         out_8(avr_addr + UART_LCR, cval | UART_LCR_DLAB);       /* set DLAB */
  75         out_8(avr_addr + UART_DLL, quot & 0xff);                /* LS of divisor */
  76         out_8(avr_addr + UART_DLM, quot >> 8);                  /* MS of divisor */
  77         out_8(avr_addr + UART_LCR, cval);                       /* reset DLAB */
  78         out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO);       /* enable FIFO */
  79 }
  80
  81 void avr_uart_send(const char c)
  82 {
  83         if (!avr_addr || !avr_clock)
  84                 return;
  85
  86         out_8(avr_addr + UART_TX, c);
  87         out_8(avr_addr + UART_TX, c);
  88         out_8(avr_addr + UART_TX, c);
  89         out_8(avr_addr + UART_TX, c);
  90 }
  91
  92 static void __init ls_uart_init(void)
  93 {
  94         local_irq_disable();
  95
  96 #ifndef CONFIG_SERIAL_8250
  97         out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO);       /* enable FIFO */
  98         out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO |
  99               UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);       /* clear FIFOs */
 100         out_8(avr_addr + UART_FCR, 0);
 101         out_8(avr_addr + UART_IER, 0);
 102
 103         /* Clear up interrupts */
 104         (void) in_8(avr_addr + UART_LSR);
 105         (void) in_8(avr_addr + UART_RX);
 106         (void) in_8(avr_addr + UART_IIR);
 107         (void) in_8(avr_addr + UART_MSR);
 108 #endif
 109         avr_uart_configure();
 110
 111         local_irq_enable();
 112 }
 113
 114 static int __init ls_uarts_init(void)
 115 {
 116         struct device_node *avr;
 117         phys_addr_t phys_addr;
 118         int len;
 119
 120         avr = of_find_node_by_path("/soc10x/serial@80004500");
 121         if (!avr)
 122                 return -EINVAL;
 123
 124         avr_clock = *(u32*)of_get_property(avr, "clock-frequency", &len);
 125         phys_addr = ((u32*)of_get_property(avr, "reg", &len))[0];
 126
 127         if (!avr_clock || !phys_addr)
 128                 return -EINVAL;
 129
 130         avr_addr = ioremap(phys_addr, 32);
 131         if (!avr_addr)
 132                 return -EFAULT;
 133
 134         ls_uart_init();
 135
 136         INIT_WORK(&wd_work, wd_stop);
 137         schedule_work(&wd_work);
 138
 139         return 0;
 140 }
 141
 142 machine_late_initcall(linkstation, ls_uarts_init);