// 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_FSstatic 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