Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/m68k/atari/stmda.c |
| 3 | * |
| 4 | * Copyright (C) 1994 Roman Hodek |
| 5 | * |
| 6 | * |
| 7 | * This file is subject to the terms and conditions of the GNU General Public |
| 8 | * License. See the file COPYING in the main directory of this archive |
| 9 | * for more details. |
| 10 | */ |
| 11 | |
| 12 | |
| 13 | /* This file contains some function for controlling the access to the */ |
| 14 | /* ST-DMA chip that may be shared between devices. Currently we have: */ |
| 15 | /* TT: Floppy and ACSI bus */ |
| 16 | /* Falcon: Floppy and SCSI */ |
| 17 | /* */ |
| 18 | /* The controlling functions set up a wait queue for access to the */ |
| 19 | /* ST-DMA chip. Callers to stdma_lock() that cannot granted access are */ |
| 20 | /* put onto a queue and waked up later if the owner calls */ |
| 21 | /* stdma_release(). Additionally, the caller gives his interrupt */ |
| 22 | /* service routine to stdma_lock(). */ |
| 23 | /* */ |
| 24 | /* On the Falcon, the IDE bus uses just the ACSI/Floppy interrupt, but */ |
| 25 | /* not the ST-DMA chip itself. So falhd.c needs not to lock the */ |
| 26 | /* chip. The interrupt is routed to falhd.c if IDE is configured, the */ |
| 27 | /* model is a Falcon and the interrupt was caused by the HD controller */ |
| 28 | /* (can be determined by looking at its status register). */ |
| 29 | |
| 30 | |
| 31 | #include <linux/types.h> |
| 32 | #include <linux/kdev_t.h> |
| 33 | #include <linux/genhd.h> |
| 34 | #include <linux/sched.h> |
| 35 | #include <linux/init.h> |
| 36 | #include <linux/interrupt.h> |
| 37 | #include <linux/wait.h> |
| 38 | |
| 39 | #include <asm/atari_stdma.h> |
| 40 | #include <asm/atariints.h> |
| 41 | #include <asm/atarihw.h> |
| 42 | #include <asm/io.h> |
| 43 | #include <asm/irq.h> |
| 44 | |
| 45 | static int stdma_locked; /* the semaphore */ |
| 46 | /* int func to be called */ |
| 47 | static irqreturn_t (*stdma_isr)(int, void *, struct pt_regs *); |
| 48 | static void *stdma_isr_data; /* data passed to isr */ |
| 49 | static DECLARE_WAIT_QUEUE_HEAD(stdma_wait); /* wait queue for ST-DMA */ |
| 50 | |
| 51 | |
| 52 | |
| 53 | |
| 54 | /***************************** Prototypes *****************************/ |
| 55 | |
| 56 | static irqreturn_t stdma_int (int irq, void *dummy, struct pt_regs *fp); |
| 57 | |
| 58 | /************************* End of Prototypes **************************/ |
| 59 | |
| 60 | |
| 61 | |
| 62 | /* |
| 63 | * Function: void stdma_lock( isrfunc isr, void *data ) |
| 64 | * |
| 65 | * Purpose: Tries to get a lock on the ST-DMA chip that is used by more |
| 66 | * then one device driver. Waits on stdma_wait until lock is free. |
| 67 | * stdma_lock() may not be called from an interrupt! You have to |
| 68 | * get the lock in your main routine and release it when your |
| 69 | * request is finished. |
| 70 | * |
| 71 | * Inputs: A interrupt function that is called until the lock is |
| 72 | * released. |
| 73 | * |
| 74 | * Returns: nothing |
| 75 | * |
| 76 | */ |
| 77 | |
| 78 | void stdma_lock(irqreturn_t (*handler)(int, void *, struct pt_regs *), |
| 79 | void *data) |
| 80 | { |
| 81 | unsigned long flags; |
| 82 | |
| 83 | local_irq_save(flags); /* protect lock */ |
| 84 | |
| 85 | /* Since the DMA is used for file system purposes, we |
| 86 | have to sleep uninterruptible (there may be locked |
| 87 | buffers) */ |
| 88 | wait_event(stdma_wait, !stdma_locked); |
| 89 | |
| 90 | stdma_locked = 1; |
| 91 | stdma_isr = handler; |
| 92 | stdma_isr_data = data; |
| 93 | local_irq_restore(flags); |
| 94 | } |
| 95 | |
| 96 | |
| 97 | /* |
| 98 | * Function: void stdma_release( void ) |
| 99 | * |
| 100 | * Purpose: Releases the lock on the ST-DMA chip. |
| 101 | * |
| 102 | * Inputs: none |
| 103 | * |
| 104 | * Returns: nothing |
| 105 | * |
| 106 | */ |
| 107 | |
| 108 | void stdma_release(void) |
| 109 | { |
| 110 | unsigned long flags; |
| 111 | |
| 112 | local_irq_save(flags); |
| 113 | |
| 114 | stdma_locked = 0; |
| 115 | stdma_isr = NULL; |
| 116 | stdma_isr_data = NULL; |
| 117 | wake_up(&stdma_wait); |
| 118 | |
| 119 | local_irq_restore(flags); |
| 120 | } |
| 121 | |
| 122 | |
| 123 | /* |
| 124 | * Function: int stdma_others_waiting( void ) |
| 125 | * |
| 126 | * Purpose: Check if someone waits for the ST-DMA lock. |
| 127 | * |
| 128 | * Inputs: none |
| 129 | * |
| 130 | * Returns: 0 if no one is waiting, != 0 otherwise |
| 131 | * |
| 132 | */ |
| 133 | |
| 134 | int stdma_others_waiting(void) |
| 135 | { |
| 136 | return waitqueue_active(&stdma_wait); |
| 137 | } |
| 138 | |
| 139 | |
| 140 | /* |
| 141 | * Function: int stdma_islocked( void ) |
| 142 | * |
| 143 | * Purpose: Check if the ST-DMA is currently locked. |
| 144 | * Note: Returned status is only valid if ints are disabled while calling and |
| 145 | * as long as they remain disabled. |
| 146 | * If called with ints enabled, status can change only from locked to |
| 147 | * unlocked, because ints may not lock the ST-DMA. |
| 148 | * |
| 149 | * Inputs: none |
| 150 | * |
| 151 | * Returns: != 0 if locked, 0 otherwise |
| 152 | * |
| 153 | */ |
| 154 | |
| 155 | int stdma_islocked(void) |
| 156 | { |
| 157 | return stdma_locked; |
| 158 | } |
| 159 | |
| 160 | |
| 161 | /* |
| 162 | * Function: void stdma_init( void ) |
| 163 | * |
| 164 | * Purpose: Initialize the ST-DMA chip access controlling. |
| 165 | * It sets up the interrupt and its service routine. The int is registered |
| 166 | * as slow int, client devices have to live with that (no problem |
| 167 | * currently). |
| 168 | * |
| 169 | * Inputs: none |
| 170 | * |
| 171 | * Return: nothing |
| 172 | * |
| 173 | */ |
| 174 | |
| 175 | void __init stdma_init(void) |
| 176 | { |
| 177 | stdma_isr = NULL; |
| 178 | request_irq(IRQ_MFP_FDC, stdma_int, IRQ_TYPE_SLOW, |
| 179 | "ST-DMA: floppy/ACSI/IDE/Falcon-SCSI", stdma_int); |
| 180 | } |
| 181 | |
| 182 | |
| 183 | /* |
| 184 | * Function: void stdma_int() |
| 185 | * |
| 186 | * Purpose: The interrupt routine for the ST-DMA. It calls the isr |
| 187 | * registered by stdma_lock(). |
| 188 | * |
| 189 | */ |
| 190 | |
| 191 | static irqreturn_t stdma_int(int irq, void *dummy, struct pt_regs *fp) |
| 192 | { |
| 193 | if (stdma_isr) |
| 194 | (*stdma_isr)(irq, stdma_isr_data, fp); |
| 195 | return IRQ_HANDLED; |
| 196 | } |