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

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * linux/arch/sh/kernel/adc.c -- SH3 on-chip ADC support
   4 *
   5 *  Copyright (C) 2004  Andriy Skulysh <askulysh@image.kiev.ua>
   6 */
   7
   8#include <linux/module.h>
   9#include <asm/adc.h>
  10#include <asm/io.h>
  11
  12
  13int adc_single(unsigned int channel)
  14{
  15        int off;
  16        unsigned char csr;
  17
  18        if (channel >= 8) return -1;
  19
  20        off = (channel & 0x03) << 2;
  21
  22        csr = __raw_readb(ADCSR);
  23        csr = channel | ADCSR_ADST | ADCSR_CKS;
  24        __raw_writeb(csr, ADCSR);
  25
  26        do {
  27                csr = __raw_readb(ADCSR);
  28        } while ((csr & ADCSR_ADF) == 0);
  29
  30        csr &= ~(ADCSR_ADF | ADCSR_ADST);
  31        __raw_writeb(csr, ADCSR);
  32
  33        return (((__raw_readb(ADDRAH + off) << 8) |
  34                __raw_readb(ADDRAL + off)) >> 6);
  35}
  36
  37EXPORT_SYMBOL(adc_single);
  38