diff options
Diffstat (limited to 'arch/arm/kernel/dma.c')
| -rw-r--r-- | arch/arm/kernel/dma.c | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/arch/arm/kernel/dma.c b/arch/arm/kernel/dma.c new file mode 100644 index 0000000000..ba15b86664 --- /dev/null +++ b/arch/arm/kernel/dma.c @@ -0,0 +1,283 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/arch/arm/kernel/dma.c + * + * Copyright (C) 1995-2000 Russell King + * + * Front-end to the DMA handling. This handles the allocation/freeing + * of DMA channels, and provides a unified interface to the machines + * DMA facilities. + */ +#include <linux/module.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/errno.h> +#include <linux/scatterlist.h> +#include <linux/seq_file.h> +#include <linux/proc_fs.h> + +#include <asm/dma.h> + +#include <asm/mach/dma.h> + +DEFINE_RAW_SPINLOCK(dma_spin_lock); +EXPORT_SYMBOL(dma_spin_lock); + +static dma_t *dma_chan[MAX_DMA_CHANNELS]; + +static inline dma_t *dma_channel(unsigned int chan) +{ + if (chan >= MAX_DMA_CHANNELS) + return NULL; + + return dma_chan[chan]; +} + +int __init isa_dma_add(unsigned int chan, dma_t *dma) +{ + if (!dma->d_ops) + return -EINVAL; + + sg_init_table(&dma->buf, 1); + + if (dma_chan[chan]) + return -EBUSY; + dma_chan[chan] = dma; + return 0; +} + +/* + * Request DMA channel + * + * On certain platforms, we have to allocate an interrupt as well... + */ +int request_dma(unsigned int chan, const char *device_id) +{ + dma_t *dma = dma_channel(chan); + int ret; + + if (!dma) + goto bad_dma; + + if (xchg(&dma->lock, 1) != 0) + goto busy; + + dma->device_id = device_id; + dma->active = 0; + dma->invalid = 1; + + ret = 0; + if (dma->d_ops->request) + ret = dma->d_ops->request(chan, dma); + + if (ret) + xchg(&dma->lock, 0); + + return ret; + +bad_dma: + pr_err("dma: trying to allocate DMA%d\n", chan); + return -EINVAL; + +busy: + return -EBUSY; +} +EXPORT_SYMBOL(request_dma); + +/* + * Free DMA channel + * + * On certain platforms, we have to free interrupt as well... + */ +void free_dma(unsigned int chan) +{ + dma_t *dma = dma_channel(chan); + + if (!dma) + goto bad_dma; + + if (dma->active) { + pr_err("dma%d: freeing active DMA\n", chan); + dma->d_ops->disable(chan, dma); + dma->active = 0; + } + + if (xchg(&dma->lock, 0) != 0) { + if (dma->d_ops->free) + dma->d_ops->free(chan, dma); + return; + } + + pr_err("dma%d: trying to free free DMA\n", chan); + return; + +bad_dma: + pr_err("dma: trying to free DMA%d\n", chan); +} +EXPORT_SYMBOL(free_dma); + +/* Set DMA Scatter-Gather list + */ +void set_dma_sg (unsigned int chan, struct scatterlist *sg, int nr_sg) +{ + dma_t *dma = dma_channel(chan); + + if (dma->active) + pr_err("dma%d: altering DMA SG while DMA active\n", chan); + + dma->sg = sg; + dma->sgcount = nr_sg; + dma->invalid = 1; +} +EXPORT_SYMBOL(set_dma_sg); + +/* Set DMA address + * + * Copy address to the structure, and set the invalid bit + */ +void __set_dma_addr (unsigned int chan, void *addr) +{ + dma_t *dma = dma_channel(chan); + + if (dma->active) + pr_err("dma%d: altering DMA address while DMA active\n", chan); + + dma->sg = NULL; + dma->addr = addr; + dma->invalid = 1; +} +EXPORT_SYMBOL(__set_dma_addr); + +/* Set DMA byte count + * + * Copy address to the structure, and set the invalid bit + */ +void set_dma_count (unsigned int chan, unsigned long count) +{ + dma_t *dma = dma_channel(chan); + + if (dma->active) + pr_err("dma%d: altering DMA count while DMA active\n", chan); + + dma->sg = NULL; + dma->count = count; + dma->invalid = 1; +} +EXPORT_SYMBOL(set_dma_count); + +/* Set DMA direction mode + */ +void set_dma_mode (unsigned int chan, unsigned int mode) +{ + dma_t *dma = dma_channel(chan); + + if (dma->active) + pr_err("dma%d: altering DMA mode while DMA active\n", chan); + + dma->dma_mode = mode; + dma->invalid = 1; +} +EXPORT_SYMBOL(set_dma_mode); + +/* Enable DMA channel + */ +void enable_dma (unsigned int chan) +{ + dma_t *dma = dma_channel(chan); + + if (!dma->lock) + goto free_dma; + + if (dma->active == 0) { + dma->active = 1; + dma->d_ops->enable(chan, dma); + } + return; + +free_dma: + pr_err("dma%d: trying to enable free DMA\n", chan); + BUG(); +} +EXPORT_SYMBOL(enable_dma); + +/* Disable DMA channel + */ +void disable_dma (unsigned int chan) +{ + dma_t *dma = dma_channel(chan); + + if (!dma->lock) + goto free_dma; + + if (dma->active == 1) { + dma->active = 0; + dma->d_ops->disable(chan, dma); + } + return; + +free_dma: + pr_err("dma%d: trying to disable free DMA\n", chan); + BUG(); +} +EXPORT_SYMBOL(disable_dma); + +/* + * Is the specified DMA channel active? + */ +int dma_channel_active(unsigned int chan) +{ + dma_t *dma = dma_channel(chan); + return dma->active; +} +EXPORT_SYMBOL(dma_channel_active); + +void set_dma_page(unsigned int chan, char pagenr) +{ + pr_err("dma%d: trying to set_dma_page\n", chan); +} +EXPORT_SYMBOL(set_dma_page); + +void set_dma_speed(unsigned int chan, int cycle_ns) +{ + dma_t *dma = dma_channel(chan); + int ret = 0; + + if (dma->d_ops->setspeed) + ret = dma->d_ops->setspeed(chan, dma, cycle_ns); + dma->speed = ret; +} +EXPORT_SYMBOL(set_dma_speed); + +int get_dma_residue(unsigned int chan) +{ + dma_t *dma = dma_channel(chan); + int ret = 0; + + if (dma->d_ops->residue) + ret = dma->d_ops->residue(chan, dma); + + return ret; +} +EXPORT_SYMBOL(get_dma_residue); + +#ifdef CONFIG_PROC_FS +static int proc_dma_show(struct seq_file *m, void *v) +{ + int i; + + for (i = 0 ; i < MAX_DMA_CHANNELS ; i++) { + dma_t *dma = dma_channel(i); + if (dma && dma->lock) + seq_printf(m, "%2d: %s\n", i, dma->device_id); + } + return 0; +} + +static int __init proc_dma_init(void) +{ + proc_create_single("dma", 0, NULL, proc_dma_show); + return 0; +} + +__initcall(proc_dma_init); +#endif |