sync_serial.c

ARM 嵌入式 系统 设计与实例开发 实验教材 二源码

	add_wait_queue(&port->out_wait_q, &wait);
	set_current_state(TASK_INTERRUPTIBLE);
	start_dma(port, buf, count);
	schedule();
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&port->out_wait_q, &wait);
	if (signal_pending(current))
	{
		return -EINTR;
	}
	return count;
}

static ssize_t sync_serial_read(struct file * file, char * buf, 
				size_t count, loff_t *ppos)
{
	int dev = MINOR(file->f_dentry->d_inode->i_rdev);
	int avail;
	sync_port *port;
	char* start; 
	char* end;
	unsigned long flags;	

	if (dev < 0 || dev >= NUMBER_OF_PORTS || !ports[dev].enabled)
	{
		DEBUG(printk("Invalid minor %d\n", dev));
		return -ENODEV;
	}
	port = &ports[dev];

	DEBUG(printk("Read dev %d count %d\n", dev, count));

	/* Make sure receiver is running */
	SETS(port->ctrl_data_shadow, R_SYNC_SERIAL1_CTRL, clk_halt, running);
	SETS(port->ctrl_data_shadow, R_SYNC_SERIAL1_CTRL, rec_enable, enable);
	*port->ctrl_data = port->ctrl_data_shadow;

	/* Calculate number of available bytes */
	while (port->readp == port->writep) /* No data */
	{
		if (file->f_flags & O_NONBLOCK)
			return -EAGAIN;
		interruptible_sleep_on(&port->in_wait_q);
		if (signal_pending(current))
		{
			return -EINTR;
		}
	}
	
	/* Save pointers to avoid that they are modified by interrupt */
	start = port->readp;
	end = port->writep;

	/* Lazy read, never return wrapped data. */
	if (end > start)
		avail = end - start;
	else 
		avail = port->in_buffer + IN_BUFFER_SIZE - start;
  
	count = count > avail ? avail : count;
	copy_to_user(buf, start, count);

	/* Disable interrupts while updating readp */
	save_flags(flags);
	cli();	
	port->readp += count;
	if (port->readp == port->in_buffer + IN_BUFFER_SIZE) /* Wrap? */
		port->readp = port->in_buffer;
	restore_flags(flags);

	DEBUG(printk("%d bytes read\n", count));
	return count;
}

static void send_word(sync_port* port)
{
	switch(port->ctrl_data_shadow & IO_MASK(R_SYNC_SERIAL1_CTRL, wordsize))
	{
		case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size8bit):
			port->out_count--;
			*port->data_out = *port->outp++;
			break;
		case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size12bit):
			port->out_count--;
			if (port->odd_output)
				*port->data_out = ((*port->outp) << 16) | (*(unsigned short *)(port->outp + 1));
			else
				*port->data_out = ((*(unsigned short *)port->outp) << 8) | (*(port->outp + 1));
			port->odd_output = !port->odd_output;
			port->outp++;
			break;
		case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size16bit):
			port->out_count-=2;
			*port->data_out = *(unsigned short *)port->outp;
			port->outp+=2;
			break;
		case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size24bit):
			port->out_count-=3;
			*port->data_out = *(unsigned int *)port->outp;
			port->outp+=3;
			break;
		case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size32bit):
			port->out_count-=4;
			*port->data_out = *(unsigned int *)port->outp;
			port->outp+=4;
			break;
	}
}

static void start_dma(struct sync_port* port, const char* data, int count)
{
	port->out_descr.hw_len = 0;
	port->out_descr.next = 0;
	port->out_descr.ctrl = d_int | d_eol | d_eop | d_wait;
	port->out_descr.sw_len = count;
	port->out_descr.buf = virt_to_phys(port->out_buffer);
	port->out_descr.status = 0;

	*port->output_dma_first = virt_to_phys(&port->out_descr);
	*port->output_dma_cmd = IO_STATE(R_DMA_CH0_CMD, cmd, start);
}

static void start_dma_in(sync_port* port)
{
	if (port->writep > port->in_buffer + IN_BUFFER_SIZE)
	{
		panic("Offset too large in sync serial driver\n");
		return;
	}
	port->in_descr1.hw_len = 0;
	port->in_descr1.ctrl = d_int;
	port->in_descr1.status = 0;
	port->in_descr1.next = virt_to_phys(&port->in_descr2);
	port->in_descr2.hw_len = 0;
	port->in_descr2.next = virt_to_phys(&port->in_descr1);
	port->in_descr2.ctrl = d_int;
	port->in_descr2.status = 0;

	/* Find out which descriptor to start */
	if (port->writep >= port->in_buffer + IN_BUFFER_SIZE/2)
	{
		/* Start descriptor 2 */
		port->in_descr1.sw_len = IN_BUFFER_SIZE/2; /* All data available in 1 */
		port->in_descr1.buf = virt_to_phys(port->in_buffer);
		port->in_descr2.sw_len = port->in_buffer + IN_BUFFER_SIZE - port->writep;
		port->in_descr2.buf = virt_to_phys(port->writep);
		*port->input_dma_first = virt_to_phys(&port->in_descr2);
	}
	else
	{
		/* Start descriptor 1 */
		port->in_descr1.sw_len = port->in_buffer + IN_BUFFER_SIZE/2 - port->writep;
		port->in_descr1.buf = virt_to_phys(port->writep);
		port->in_descr2.sw_len = IN_BUFFER_SIZE/2;
		port->in_descr2.buf = virt_to_phys(port->in_buffer + IN_BUFFER_SIZE / 2);
		*port->input_dma_first = virt_to_phys(&port->in_descr1);
	}
	*port->input_dma_cmd = IO_STATE(R_DMA_CH0_CMD, cmd, start);
}

static void tr_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	unsigned long ireg = *R_IRQ_MASK2_RD;
	int i;

	for (i = 0; i < NUMBER_OF_PORTS; i++) 
	{
		sync_port *port = &ports[i];
		if (ireg & (1 << port->output_dma_bit)) /* IRQ active for the port? */
		{
			/* Clear IRQ */
			*port->output_dma_clr_irq = 
			  IO_STATE(R_DMA_CH0_CLR_INTR, clr_eop, do) |
			  IO_STATE(R_DMA_CH0_CLR_INTR, clr_descr, do);
			wake_up_interruptible(&port->out_wait_q); /* wake up the waiting process */
		} 
	}
}

static void rx_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	unsigned long ireg = *R_IRQ_MASK2_RD;
	int i;	

	for (i = 0; i < NUMBER_OF_PORTS; i++) 
	{
		int update = 0;
		sync_port *port = &ports[i];

		if (!port->enabled)
		{
			continue;
		}    

		if (ireg & (1 << port->input_dma_descr_bit)) /* Descriptor interrupt */
		{
			/* DMA has reached end of descriptor */
			*port->input_dma_clr_irq = 
			  IO_STATE(R_DMA_CH0_CLR_INTR, clr_eop, do) | 
			  IO_STATE(R_DMA_CH0_CLR_INTR, clr_descr, do);

			/* Find out which descriptor that is ready */
			if (port->writep >= port->in_buffer + IN_BUFFER_SIZE/2) 
			{
				/* Descr 2 was ready. Restart DMA at descriptor 1 */
				port->writep = port->in_buffer;
	
				/* Throw away data? */
				if (port->readp < port->in_buffer + IN_BUFFER_SIZE/2)
					port->readp = port->in_buffer + IN_BUFFER_SIZE/2;
			}
			else
			{
				/* Descr 1 was ready. Restart DMA at descriptor 2 */
				port->writep = port->in_buffer + IN_BUFFER_SIZE/2;

				/* Throw away data? */
				if (port->readp >= port->in_buffer + IN_BUFFER_SIZE/2)
					port->readp = port->in_buffer;
			}
			start_dma_in(port);
			wake_up_interruptible(&port->in_wait_q); /* wake up the waiting process */
		}
	}
}

static void manual_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	int i;

	for (i = 0; i < NUMBER_OF_PORTS; i++)
	{
		sync_port* port = &ports[i];

		if (!port->enabled)
		{
			continue;
		}

		if (*R_IRQ_MASK1_RD & (1 << port->data_avail_bit))	/* Data received? */
		{
			/* Read data */
			switch(port->ctrl_data_shadow & IO_MASK(R_SYNC_SERIAL1_CTRL, wordsize))
			{
				case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size8bit):
					*port->writep++ = *(volatile char *)port->data_in;
					break;
				case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size12bit):
				{
					int data = *(unsigned short *)port->data_in;
					if (port->odd_input)
					{
						*port->writep |= (data & 0x0f00) >> 8;
						*(port->writep + 1) = data & 0xff;
					}
					else
					{
						*port->writep = (data & 0x0ff0) >> 4;
						*(port->writep + 1) = (data & 0x0f) << 4;
					}
					port->odd_input = !port->odd_input;
					port->writep+=1;
				}
				break;
				case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size16bit):
					*(unsigned short*)port->writep = *(volatile unsigned short *)port->data_in;
					port->writep+=2;
					break;
				case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size24bit):
					*(unsigned int*)port->writep = *port->data_in;
					port->writep+=3;
					break;
				case IO_STATE(R_SYNC_SERIAL1_CTRL, wordsize, size32bit):
					*(unsigned int*)port->writep = *port->data_in;
					port->writep+=4;
					break;
			}

			if (port->writep > port->in_buffer + IN_BUFFER_SIZE) /* Wrap? */
				port->writep = port->in_buffer;
			wake_up_interruptible(&port->in_wait_q); /* Wake up application */
		}

		if (*R_IRQ_MASK1_RD & (1 << port->transmitter_ready_bit)) /* Transmitter ready? */
		{
			if (port->out_count) /* More data to send */
				send_word(port);
			else /* transmission finished */
			{
				*R_IRQ_MASK1_CLR = 1 << port->ready_irq_bit; /* Turn off IRQ */
				wake_up_interruptible(&port->out_wait_q); /* Wake up application */
			}
		}
	}
}

module_init(etrax_sync_serial_init);