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 
adc_single(unsigned int channel)13 int 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 
37 EXPORT_SYMBOL(adc_single);
38