soc/codecs/l3.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * L3 code
0004  *
0005  *  Copyright (C) 2008, Christian Pellegrin <chripell@evolware.org>
0006  *
0007  * based on:
0008  *
0009  * L3 bus algorithm module.
0010  *
0011  *  Copyright (C) 2001 Russell King, All Rights Reserved.
0012  */
0013
0014 #include <linux/module.h>
0015 #include <linux/kernel.h>
0016 #include <linux/delay.h>
0017 #include <linux/device.h>
0018 #include <linux/gpio.h>
0019
0020 #include <sound/l3.h>
0021
0022 /*
0023  * Send one byte of data to the chip.  Data is latched into the chip on
0024  * the rising edge of the clock.
0025  */
0026 static void sendbyte(struct l3_pins *adap, unsigned int byte)
0027 {
0028     int i;
0029
0030     for (i = 0; i < 8; i++) {
0031         adap->setclk(adap, 0);
0032         udelay(adap->data_hold);
0033         adap->setdat(adap, byte & 1);
0034         udelay(adap->data_setup);
0035         adap->setclk(adap, 1);
0036         udelay(adap->clock_high);
0037         byte >>= 1;
0038     }
0039 }
0040
0041 /*
0042  * Send a set of bytes to the chip.  We need to pulse the MODE line
0043  * between each byte, but never at the start nor at the end of the
0044  * transfer.
0045  */
0046 static void sendbytes(struct l3_pins *adap, const u8 *buf,
0047               int len)
0048 {
0049     int i;
0050
0051     for (i = 0; i < len; i++) {
0052         if (i) {
0053             udelay(adap->mode_hold);
0054             adap->setmode(adap, 0);
0055             udelay(adap->mode);
0056         }
0057         adap->setmode(adap, 1);
0058         udelay(adap->mode_setup);
0059         sendbyte(adap, buf[i]);
0060     }
0061 }
0062
0063 int l3_write(struct l3_pins *adap, u8 addr, u8 *data, int len)
0064 {
0065     adap->setclk(adap, 1);
0066     adap->setdat(adap, 1);
0067     adap->setmode(adap, 1);
0068     udelay(adap->mode);
0069
0070     adap->setmode(adap, 0);
0071     udelay(adap->mode_setup);
0072     sendbyte(adap, addr);
0073     udelay(adap->mode_hold);
0074
0075     sendbytes(adap, data, len);
0076
0077     adap->setclk(adap, 1);
0078     adap->setdat(adap, 1);
0079     adap->setmode(adap, 0);
0080
0081     return len;
0082 }
0083 EXPORT_SYMBOL_GPL(l3_write);
0084
0085
0086 static void l3_set_clk(struct l3_pins *adap, int val)
0087 {
0088     gpio_set_value(adap->gpio_clk, val);
0089 }
0090
0091 static void l3_set_data(struct l3_pins *adap, int val)
0092 {
0093     gpio_set_value(adap->gpio_data, val);
0094 }
0095
0096 static void l3_set_mode(struct l3_pins *adap, int val)
0097 {
0098     gpio_set_value(adap->gpio_mode, val);
0099 }
0100
0101 int l3_set_gpio_ops(struct device *dev, struct l3_pins *adap)
0102 {
0103     int ret;
0104
0105     if (!adap->use_gpios)
0106         return -EINVAL;
0107
0108     ret = devm_gpio_request_one(dev, adap->gpio_data,
0109                 GPIOF_OUT_INIT_LOW, "l3_data");
0110     if (ret < 0)
0111         return ret;
0112     adap->setdat = l3_set_data;
0113
0114     ret = devm_gpio_request_one(dev, adap->gpio_clk,
0115                 GPIOF_OUT_INIT_LOW, "l3_clk");
0116     if (ret < 0)
0117         return ret;
0118     adap->setclk = l3_set_clk;
0119
0120     ret = devm_gpio_request_one(dev, adap->gpio_mode,
0121                 GPIOF_OUT_INIT_LOW, "l3_mode");
0122     if (ret < 0)
0123         return ret;
0124     adap->setmode = l3_set_mode;
0125
0126     return 0;
0127 }
0128 EXPORT_SYMBOL_GPL(l3_set_gpio_ops);
0129
0130 MODULE_DESCRIPTION("L3 bit-banging driver");
0131 MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
0132 MODULE_LICENSE("GPL");