| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* |
| 3 | * ISA DMA support functions |
| 4 | * Copyright (c) by Jaroslav Kysela <perex@perex.cz> |
| 5 | */ |
| 6 | |
| 7 | /* |
| 8 | * Defining following add some delay. Maybe this helps for some broken |
| 9 | * ISA DMA controllers. |
| 10 | */ |
| 11 | |
| 12 | #undef HAVE_REALLY_SLOW_DMA_CONTROLLER |
| 13 | |
| 14 | #include <linux/export.h> |
| 15 | #include <linux/isa-dma.h> |
| 16 | #include <sound/core.h> |
| 17 | |
| 18 | /** |
| 19 | * snd_dma_program - program an ISA DMA transfer |
| 20 | * @dma: the dma number |
| 21 | * @addr: the physical address of the buffer |
| 22 | * @size: the DMA transfer size |
| 23 | * @mode: the DMA transfer mode, DMA_MODE_XXX |
| 24 | * |
| 25 | * Programs an ISA DMA transfer for the given buffer. |
| 26 | */ |
| 27 | void snd_dma_program(unsigned long dma, |
| 28 | unsigned long addr, unsigned int size, |
| 29 | unsigned short mode) |
| 30 | { |
| 31 | unsigned long flags; |
| 32 | |
| 33 | flags = claim_dma_lock(); |
| 34 | disable_dma(dma); |
| 35 | clear_dma_ff(dma); |
| 36 | set_dma_mode(dma, mode); |
| 37 | set_dma_addr(dma, addr); |
| 38 | set_dma_count(dma, size); |
| 39 | if (!(mode & DMA_MODE_NO_ENABLE)) |
| 40 | enable_dma(dma); |
| 41 | release_dma_lock(flags); |
| 42 | } |
| 43 | EXPORT_SYMBOL(snd_dma_program); |
| 44 | |
| 45 | /** |
| 46 | * snd_dma_disable - stop the ISA DMA transfer |
| 47 | * @dma: the dma number |
| 48 | * |
| 49 | * Stops the ISA DMA transfer. |
| 50 | */ |
| 51 | void snd_dma_disable(unsigned long dma) |
| 52 | { |
| 53 | unsigned long flags; |
| 54 | |
| 55 | flags = claim_dma_lock(); |
| 56 | clear_dma_ff(dma); |
| 57 | disable_dma(dma); |
| 58 | release_dma_lock(flags); |
| 59 | } |
| 60 | EXPORT_SYMBOL(snd_dma_disable); |
| 61 | |
| 62 | /** |
| 63 | * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes |
| 64 | * @dma: the dma number |
| 65 | * @size: the dma transfer size |
| 66 | * |
| 67 | * Return: The current pointer in DMA transfer buffer in bytes. |
| 68 | */ |
| 69 | unsigned int snd_dma_pointer(unsigned long dma, unsigned int size) |
| 70 | { |
| 71 | unsigned long flags; |
| 72 | unsigned int result, result1; |
| 73 | |
| 74 | flags = claim_dma_lock(); |
| 75 | clear_dma_ff(dma); |
| 76 | if (!isa_dma_bridge_buggy) |
| 77 | disable_dma(dma); |
| 78 | result = get_dma_residue(dma); |
| 79 | /* |
| 80 | * HACK - read the counter again and choose higher value in order to |
| 81 | * avoid reading during counter lower byte roll over if the |
| 82 | * isa_dma_bridge_buggy is set. |
| 83 | */ |
| 84 | result1 = get_dma_residue(dma); |
| 85 | if (!isa_dma_bridge_buggy) |
| 86 | enable_dma(dma); |
| 87 | release_dma_lock(flags); |
| 88 | if (unlikely(result < result1)) |
| 89 | result = result1; |
| 90 | #ifdef CONFIG_SND_DEBUG |
| 91 | if (result > size) |
| 92 | pr_err("ALSA: pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size); |
| 93 | #endif |
| 94 | if (result >= size || result == 0) |
| 95 | return 0; |
| 96 | else |
| 97 | return size - result; |
| 98 | } |
| 99 | EXPORT_SYMBOL(snd_dma_pointer); |
| 100 | |
| 101 | struct snd_dma_data { |
| 102 | int dma; |
| 103 | }; |
| 104 | |
| 105 | static void __snd_release_dma(struct device *dev, void *data) |
| 106 | { |
| 107 | struct snd_dma_data *p = data; |
| 108 | |
| 109 | snd_dma_disable(p->dma); |
| 110 | free_dma(p->dma); |
| 111 | } |
| 112 | |
| 113 | /** |
| 114 | * snd_devm_request_dma - the managed version of request_dma() |
| 115 | * @dev: the device pointer |
| 116 | * @dma: the dma number |
| 117 | * @name: the name string of the requester |
| 118 | * |
| 119 | * The requested DMA will be automatically released at unbinding via devres. |
| 120 | * |
| 121 | * Return: zero on success, or a negative error code |
| 122 | */ |
| 123 | int snd_devm_request_dma(struct device *dev, int dma, const char *name) |
| 124 | { |
| 125 | struct snd_dma_data *p; |
| 126 | |
| 127 | if (request_dma(dma, name)) |
| 128 | return -EBUSY; |
| 129 | p = devres_alloc(__snd_release_dma, sizeof(*p), GFP_KERNEL); |
| 130 | if (!p) { |
| 131 | free_dma(dma); |
| 132 | return -ENOMEM; |
| 133 | } |
| 134 | p->dma = dma; |
| 135 | devres_add(dev, p); |
| 136 | return 0; |
| 137 | } |
| 138 | EXPORT_SYMBOL_GPL(snd_devm_request_dma); |