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
  12 int 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
  36 EXPORT_SYMBOL(adc_single);