drivers/spi/lpc21xx_spi.c

   1 /* Author: Domen Puncer <domen@cba.si>.  License: WTFPL, see file LICENSE */
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <errno.h>
   5
   6 #include <interrupt.h>
   7 #include <types.h>
   8 #include <gpio.h>
   9 #include <compiler.h>
  10 #include <mach/lpc21xx_gpio.h>
  11 #include <mach/lpc21xx_regs.h>
  12 #include <drivers/spi.h>
  13 #include <drivers/lpc_spi.h>
  14
  15
  16
  17 static int lpc_spi_change_device(struct spi_device *device)
  18 {
  19         struct lpc_spi *spi = device->master->spi;
  20         struct lpc_spi_data *data = device->master->spi_data;
  21         int tmp;
  22         int spi_cr = 0;
  23
  24         if (device->mode & SPI_CPHA)
  25                 spi_cr |= 1<<3;
  26         if (device->mode & SPI_CPOL)
  27                 spi_cr |= 1<<4;
  28         spi_cr |= 1<<5; /* MSTR master mode */
  29         if (device->mode & SPI_LSB)
  30                 spi_cr |= 1<<6; /* LSBF LSB first */
  31
  32         spi_cr |= 1<<7; /* SPIE interrupt enable */
  33         spi->SPINT = 1; /* clear old interrupt */
  34         irq_enable(IRQ_SPI0);
  35
  36         spi->SPCR = spi_cr;
  37         tmp = (data->pclk + device->clock-1) / device->clock;
  38         tmp &= ~1;
  39         if (tmp < 8)
  40                 tmp = 8;
  41         if (tmp > 255)
  42                 tmp = 254;
  43         /* this limits spi clock to pclk/8 */
  44         spi->SPCCR = tmp;
  45
  46         gpio_init(device->cs_pin, GPIO_OUTPUT, 1);
  47
  48         return 0;
  49 }
  50
  51 static void lpc_spi_tx(struct lpc_spi *spi, u8 data)
  52 {
  53         spi->SPDR = data;
  54 }
  55
  56 static struct spi0_irq_data {
  57         struct spi_device *device;
  58         struct spi_transfer *transfer;
  59         int pos;
  60 } spi0_irq_data;
  61
  62 void __interrupt spi0_handler()
  63 {
  64         struct lpc_spi *spi = spi0_irq_data.device->master->spi;
  65         struct spi_transfer *transfer = spi0_irq_data.transfer;
  66         int pos = spi0_irq_data.pos;
  67
  68         spi->SPINT = 1; /* clear spi interrupt */
  69         VICVectAddr = 0; /* clear pending interrupt */
  70
  71         if ((spi->SPSR & 1<<7) == 0) {
  72                 printf("%s: should error out with spi_transfer_finished\n", __func__);
  73                 transfer->error = -EINVAL;
  74                 spi_transfer_finished(spi0_irq_data.device, transfer);
  75                 return;
  76         }
  77         transfer->rx_buf[pos++] = spi->SPDR;
  78
  79         if (pos >= transfer->len) {
  80                 gpio_set(spi0_irq_data.device->cs_pin, 1);
  81                 spi_transfer_finished(spi0_irq_data.device, transfer);
  82         } else {
  83                 lpc_spi_tx(spi, transfer->tx_buf[pos]);
  84         }
  85
  86         spi0_irq_data.pos = pos;
  87 }
  88
  89 static int lpc_spi_transfer(struct spi_device *device, struct spi_transfer *transfer)
  90 {
  91         struct lpc_spi *spi = device->master->spi;
  92
  93         spi0_irq_data.pos = 0;
  94         spi0_irq_data.device = device;
  95         spi0_irq_data.transfer = transfer;
  96
  97         gpio_set(device->cs_pin, 0);
  98         lpc_spi_tx(spi, transfer->tx_buf[0]);
  99
 100         /* after this, the irq routine picks up */
 101
 102         return 0;
 103 }
 104
 105
 106 int lpc_spi_register(struct spi_master *master)
 107 {
 108         /* some init goes here... which isn't needed in this case */
 109
 110         master->change_device = lpc_spi_change_device;
 111         master->transfer = lpc_spi_transfer;
 112         return 0;
 113 }