1 /* 2 * 8237A DMA controller suspend functions. 3 * 4 * Written by Pierre Ossman, 2005. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or (at 9 * your option) any later version. 10 */ 11 12 #include <linux/init.h> 13 #include <linux/sysdev.h> 14 15 #include <asm/dma.h> 16 17 /* 18 * This module just handles suspend/resume issues with the 19 * 8237A DMA controller (used for ISA and LPC). 20 * Allocation is handled in kernel/dma.c and normal usage is 21 * in asm/dma.h. 22 */ 23 24 static int i8237A_resume(struct sys_device *dev) 25 { 26 unsigned long flags; 27 int i; 28 29 flags = claim_dma_lock(); 30 31 dma_outb(0, DMA1_RESET_REG); 32 dma_outb(0, DMA2_RESET_REG); 33 34 for (i = 0; i < 8; i++) { 35 set_dma_addr(i, 0x000000); 36 /* DMA count is a bit weird so this is not 0 */ 37 set_dma_count(i, 1); 38 } 39 40 /* Enable cascade DMA or channel 0-3 won't work */ 41 enable_dma(4); 42 43 release_dma_lock(flags); 44 45 return 0; 46 } 47 48 static int i8237A_suspend(struct sys_device *dev, pm_message_t state) 49 { 50 return 0; 51 } 52 53 static struct sysdev_class i8237_sysdev_class = { 54 .name = "i8237", 55 .suspend = i8237A_suspend, 56 .resume = i8237A_resume, 57 }; 58 59 static struct sys_device device_i8237A = { 60 .id = 0, 61 .cls = &i8237_sysdev_class, 62 }; 63 64 static int __init i8237A_init_sysfs(void) 65 { 66 int error = sysdev_class_register(&i8237_sysdev_class); 67 if (!error) 68 error = sysdev_register(&device_i8237A); 69 return error; 70 } 71 device_initcall(i8237A_init_sysfs); 72