text: /* SPDX-License-Identifier: GPL-2.0 */
  #ifndef __ASM_ARM_DMA_H
  #define __ASM_ARM_DMA_H
  
  /*
   * This is the maximum virtual address which can be DMA'd from.
   */
  #ifndef CONFIG_ZONE_DMA
  #define MAX_DMA_ADDRESS	0xffffffffUL
  #else
  #define MAX_DMA_ADDRESS	({ \
  	extern phys_addr_t arm_dma_zone_size; \
  	arm_dma_zone_size && arm_dma_zone_size < (0x10000000 - PAGE_OFFSET) ? \
  		(PAGE_OFFSET + arm_dma_zone_size) : 0xffffffffUL; })
  #endif
  
  #ifdef CONFIG_ISA_DMA_API
  /*
   * This is used to support drivers written for the x86 ISA DMA API.
   * It should not be re-used except for that purpose.
   */
  #include <linux/spinlock.h>
  #include <linux/scatterlist.h>
  
  #include <mach/isa-dma.h>
  
  /*
   * The DMA modes reflect the settings for the ISA DMA controller
   */
  #define DMA_MODE_MASK	 0xcc
  
  #define DMA_MODE_READ	 0x44
  #define DMA_MODE_WRITE	 0x48
  #define DMA_MODE_CASCADE 0xc0
  #define DMA_AUTOINIT	 0x10
  
  extern raw_spinlock_t  dma_spin_lock;
  
  static inline unsigned long claim_dma_lock(void)
  {
  	unsigned long flags;
  	raw_spin_lock_irqsave(&dma_spin_lock, flags);
  	return flags;
  }
  
  static inline void release_dma_lock(unsigned long flags)
  {
  	raw_spin_unlock_irqrestore(&dma_spin_lock, flags);
  }
  
  /* Clear the 'DMA Pointer Flip Flop'.
   * Write 0 for LSB/MSB, 1 for MSB/LSB access.
   */
  #define clear_dma_ff(chan)
  
  /* Set only the page register bits of the transfer address.
   *
   * NOTE: This is an architecture specific function, and should
   *       be hidden from the drivers
   */
  extern void set_dma_page(unsigned int chan, char pagenr);
  
  /* Request a DMA channel
   *
   * Some architectures may need to do allocate an interrupt
   */
  extern int  request_dma(unsigned int chan, const char * device_id);
  
  /* Free a DMA channel
   *
   * Some architectures may need to do free an interrupt
   */
  extern void free_dma(unsigned int chan);
  
  /* Enable DMA for this channel
   *
   * On some architectures, this may have other side effects like
   * enabling an interrupt and setting the DMA registers.
   */
  extern void enable_dma(unsigned int chan);
  
  /* Disable DMA for this channel
   *
   * On some architectures, this may have other side effects like
   * disabling an interrupt or whatever.
   */
  extern void disable_dma(unsigned int chan);
  
  /* Test whether the specified channel has an active DMA transfer
   */
  extern int dma_channel_active(unsigned int chan);
  
  /* Set the DMA scatter gather list for this channel
   *
   * This should not be called if a DMA channel is enabled,
   * especially since some DMA architectures don't update the
   * DMA address immediately, but defer it to the enable_dma().
   */
  extern void set_dma_sg(unsigned int chan, struct scatterlist *sg, int nr_sg);
  
  /* Set the DMA address for this channel
   *
   * This should not be called if a DMA channel is enabled,
   * especially since some DMA architectures don't update the
   * DMA address immediately, but defer it to the enable_dma().
   */
  extern void __set_dma_addr(unsigned int chan, void *addr);
  #define set_dma_addr(chan, addr)				\
  	__set_dma_addr(chan, (void *)__bus_to_virt(addr))
  
  /* Set the DMA byte count for this channel
   *
   * This should not be called if a DMA channel is enabled,
   * especially since some DMA architectures don't update the
   * DMA count immediately, but defer it to the enable_dma().
   */
  extern void set_dma_count(unsigned int chan, unsigned long count);
  
  /* Set the transfer direction for this channel
   *
   * This should not be called if a DMA channel is enabled,
   * especially since some DMA architectures don't update the
   * DMA transfer direction immediately, but defer it to the
   * enable_dma().
   */
  extern void set_dma_mode(unsigned int chan, unsigned int mode);
  
  /* Set the transfer speed for this channel
   */
  extern void set_dma_speed(unsigned int chan, int cycle_ns);
  
  /* Get DMA residue count. After a DMA transfer, this
   * should return zero. Reading this while a DMA transfer is
   * still in progress will return unpredictable results.
   * If called before the channel has been used, it may return 1.
   * Otherwise, it returns the number of _bytes_ left to transfer.
   */
  extern int  get_dma_residue(unsigned int chan);
  
  #ifndef NO_DMA
  #define NO_DMA	255
  #endif
  
  #endif /* CONFIG_ISA_DMA_API */
  
  #ifdef CONFIG_PCI
  extern int isa_dma_bridge_buggy;
  #else
  #define isa_dma_bridge_buggy    (0)
  #endif
  
  #endif /* __ASM_ARM_DMA_H */
  