LXR linux/arch/sh/kernel/cpu/adc.c

   1/*
   2 * linux/arch/sh/kernel/adc.c -- SH3 on-chip ADC support
   3 *
   4 *  Copyright (C) 2004  Andriy Skulysh <askulysh@image.kiev.ua>
   5 */
   6
   7#include <linux/module.h>
   8#include <asm/adc.h>
   9#include <asm/io.h>
  10
  11
  12int adc_single(unsigned int channel)
  13{
  14        int off;
  15        unsigned char csr;
  16
  17        if (channel >= 8) return -1;
  18
  19        off = (channel & 0x03) << 2;
  20
  21        csr = __raw_readb(ADCSR);
  22        csr = channel | ADCSR_ADST | ADCSR_CKS;
  23        __raw_writeb(csr, ADCSR);
  24
  25        do {
  26                csr = __raw_readb(ADCSR);
  27        } while ((csr & ADCSR_ADF) == 0);
  28
  29        csr &= ~(ADCSR_ADF | ADCSR_ADST);
  30        __raw_writeb(csr, ADCSR);
  31
  32        return (((__raw_readb(ADDRAH + off) << 8) |
  33                __raw_readb(ADDRAL + off)) >> 6);
  34}
  35
  36EXPORT_SYMBOL(adc_single);
  37