1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * L3 code
4 *
5 * Copyright (C) 2008, Christian Pellegrin <chripell@evolware.org>
6 *
7 * based on:
8 *
9 * L3 bus algorithm module.
10 *
11 * Copyright (C) 2001 Russell King, All Rights Reserved.
12 */
13
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/delay.h>
17 #include <linux/device.h>
18 #include <linux/gpio.h>
19
20 #include <sound/l3.h>
21
22 /*
23 * Send one byte of data to the chip. Data is latched into the chip on
24 * the rising edge of the clock.
25 */
sendbyte(struct l3_pins * adap,unsigned int byte)26 static void sendbyte(struct l3_pins *adap, unsigned int byte)
27 {
28 int i;
29
30 for (i = 0; i < 8; i++) {
31 adap->setclk(adap, 0);
32 udelay(adap->data_hold);
33 adap->setdat(adap, byte & 1);
34 udelay(adap->data_setup);
35 adap->setclk(adap, 1);
36 udelay(adap->clock_high);
37 byte >>= 1;
38 }
39 }
40
41 /*
42 * Send a set of bytes to the chip. We need to pulse the MODE line
43 * between each byte, but never at the start nor at the end of the
44 * transfer.
45 */
sendbytes(struct l3_pins * adap,const u8 * buf,int len)46 static void sendbytes(struct l3_pins *adap, const u8 *buf,
47 int len)
48 {
49 int i;
50
51 for (i = 0; i < len; i++) {
52 if (i) {
53 udelay(adap->mode_hold);
54 adap->setmode(adap, 0);
55 udelay(adap->mode);
56 }
57 adap->setmode(adap, 1);
58 udelay(adap->mode_setup);
59 sendbyte(adap, buf[i]);
60 }
61 }
62
l3_write(struct l3_pins * adap,u8 addr,u8 * data,int len)63 int l3_write(struct l3_pins *adap, u8 addr, u8 *data, int len)
64 {
65 adap->setclk(adap, 1);
66 adap->setdat(adap, 1);
67 adap->setmode(adap, 1);
68 udelay(adap->mode);
69
70 adap->setmode(adap, 0);
71 udelay(adap->mode_setup);
72 sendbyte(adap, addr);
73 udelay(adap->mode_hold);
74
75 sendbytes(adap, data, len);
76
77 adap->setclk(adap, 1);
78 adap->setdat(adap, 1);
79 adap->setmode(adap, 0);
80
81 return len;
82 }
83 EXPORT_SYMBOL_GPL(l3_write);
84
85
l3_set_clk(struct l3_pins * adap,int val)86 static void l3_set_clk(struct l3_pins *adap, int val)
87 {
88 gpio_set_value(adap->gpio_clk, val);
89 }
90
l3_set_data(struct l3_pins * adap,int val)91 static void l3_set_data(struct l3_pins *adap, int val)
92 {
93 gpio_set_value(adap->gpio_data, val);
94 }
95
l3_set_mode(struct l3_pins * adap,int val)96 static void l3_set_mode(struct l3_pins *adap, int val)
97 {
98 gpio_set_value(adap->gpio_mode, val);
99 }
100
l3_set_gpio_ops(struct device * dev,struct l3_pins * adap)101 int l3_set_gpio_ops(struct device *dev, struct l3_pins *adap)
102 {
103 int ret;
104
105 if (!adap->use_gpios)
106 return -EINVAL;
107
108 ret = devm_gpio_request_one(dev, adap->gpio_data,
109 GPIOF_OUT_INIT_LOW, "l3_data");
110 if (ret < 0)
111 return ret;
112 adap->setdat = l3_set_data;
113
114 ret = devm_gpio_request_one(dev, adap->gpio_clk,
115 GPIOF_OUT_INIT_LOW, "l3_clk");
116 if (ret < 0)
117 return ret;
118 adap->setclk = l3_set_clk;
119
120 ret = devm_gpio_request_one(dev, adap->gpio_mode,
121 GPIOF_OUT_INIT_LOW, "l3_mode");
122 if (ret < 0)
123 return ret;
124 adap->setmode = l3_set_mode;
125
126 return 0;
127 }
128 EXPORT_SYMBOL_GPL(l3_set_gpio_ops);
129
130 MODULE_DESCRIPTION("L3 bit-banging driver");
131 MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
132 MODULE_LICENSE("GPL");
133