1/*
2 * L3 code
3 *
4 *  Copyright (C) 2008, Christian Pellegrin <chripell@evolware.org>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 *
11 * based on:
12 *
13 * L3 bus algorithm module.
14 *
15 *  Copyright (C) 2001 Russell King, All Rights Reserved.
16 *
17 *
18 */
19
20#include <linux/module.h>
21#include <linux/kernel.h>
22#include <linux/delay.h>
23
24#include <sound/l3.h>
25
26/*
27 * Send one byte of data to the chip.  Data is latched into the chip on
28 * the rising edge of the clock.
29 */
30static void sendbyte(struct l3_pins *adap, unsigned int byte)
31{
32	int i;
33
34	for (i = 0; i < 8; i++) {
35		adap->setclk(0);
36		udelay(adap->data_hold);
37		adap->setdat(byte & 1);
38		udelay(adap->data_setup);
39		adap->setclk(1);
40		udelay(adap->clock_high);
41		byte >>= 1;
42	}
43}
44
45/*
46 * Send a set of bytes to the chip.  We need to pulse the MODE line
47 * between each byte, but never at the start nor at the end of the
48 * transfer.
49 */
50static void sendbytes(struct l3_pins *adap, const u8 *buf,
51		      int len)
52{
53	int i;
54
55	for (i = 0; i < len; i++) {
56		if (i) {
57			udelay(adap->mode_hold);
58			adap->setmode(0);
59			udelay(adap->mode);
60		}
61		adap->setmode(1);
62		udelay(adap->mode_setup);
63		sendbyte(adap, buf[i]);
64	}
65}
66
67int l3_write(struct l3_pins *adap, u8 addr, u8 *data, int len)
68{
69	adap->setclk(1);
70	adap->setdat(1);
71	adap->setmode(1);
72	udelay(adap->mode);
73
74	adap->setmode(0);
75	udelay(adap->mode_setup);
76	sendbyte(adap, addr);
77	udelay(adap->mode_hold);
78
79	sendbytes(adap, data, len);
80
81	adap->setclk(1);
82	adap->setdat(1);
83	adap->setmode(0);
84
85	return len;
86}
87EXPORT_SYMBOL_GPL(l3_write);
88
89MODULE_DESCRIPTION("L3 bit-banging driver");
90MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
91MODULE_LICENSE("GPL");
92