1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * I2C driver for stand-alone PCF8584 style adapters on Zorro cards
  4 *
  5 * Original ICY documentation can be found on Aminet:
  6 * https://aminet.net/package/docs/hard/icy
  7 *
  8 * There has been a modern community re-print of this design in 2019:
  9 * https://www.a1k.org/forum/index.php?threads/70106/
 10 *
 11 * The card is basically a Philips PCF8584 connected straight to the
 12 * beginning of the AutoConfig'd address space (register S1 on base+2),
 13 * with /INT on /INT2 on the Zorro bus.
 14 *
 15 * Copyright (c) 2019 Max Staudt <max@enpas.org>
 16 *
 17 * This started as a fork of i2c-elektor.c and has evolved since.
 18 * Thanks go to its authors for providing a base to grow on.
 19 *
 20 *
 21 * IRQ support is currently not implemented.
 22 *
 23 * As it turns out, i2c-algo-pcf is really written with i2c-elektor's
 24 * edge-triggered ISA interrupts in mind, while the Amiga's Zorro bus has
 25 * level-triggered interrupts. This means that once an interrupt occurs, we
 26 * have to tell the PCF8584 to shut up immediately, or it will keep the
 27 * interrupt line busy and cause an IRQ storm.
 28
 29 * However, because of the PCF8584's host-side protocol, there is no good
 30 * way to just quieten it without side effects. Rather, we have to perform
 31 * the next read/write operation straight away, which will reset the /INT
 32 * pin. This entails re-designing the core of i2c-algo-pcf in the future.
 33 * For now, we never request an IRQ from the PCF8584, and poll it instead.
 34 */
 35
 36#include <linux/delay.h>
 37#include <linux/init.h>
 38#include <linux/io.h>
 39#include <linux/ioport.h>
 40#include <linux/kernel.h>
 41#include <linux/module.h>
 42
 43#include <linux/i2c.h>
 44#include <linux/i2c-algo-pcf.h>
 45
 46#include <asm/amigahw.h>
 47#include <asm/amigaints.h>
 48#include <linux/zorro.h>
 49
 50#include "../algos/i2c-algo-pcf.h"
 51
 52struct icy_i2c {
 53	struct i2c_adapter adapter;
 54
 55	void __iomem *reg_s0;
 56	void __iomem *reg_s1;
 57	struct i2c_client *ltc2990_client;
 58};
 59
 60/*
 61 * Functions called by i2c-algo-pcf
 62 */
 63static void icy_pcf_setpcf(void *data, int ctl, int val)
 64{
 65	struct icy_i2c *i2c = (struct icy_i2c *)data;
 66
 67	u8 __iomem *address = ctl ? i2c->reg_s1 : i2c->reg_s0;
 68
 69	z_writeb(val, address);
 70}
 71
 72static int icy_pcf_getpcf(void *data, int ctl)
 73{
 74	struct icy_i2c *i2c = (struct icy_i2c *)data;
 75
 76	u8 __iomem *address = ctl ? i2c->reg_s1 : i2c->reg_s0;
 77
 78	return z_readb(address);
 79}
 80
 81static int icy_pcf_getown(void *data)
 82{
 83	return 0x55;
 84}
 85
 86static int icy_pcf_getclock(void *data)
 87{
 88	return 0x1c;
 89}
 90
 91static void icy_pcf_waitforpin(void *data)
 92{
 93	usleep_range(50, 150);
 94}
 95
 96/*
 97 * Main i2c-icy part
 98 */
 99static unsigned short const icy_ltc2990_addresses[] = {
100	0x4c, 0x4d, 0x4e, 0x4f, I2C_CLIENT_END
101};
102
103/*
104 * Additional sensors exposed once this property is applied:
105 *
106 * in1 will be the voltage of the 5V rail, divided by 2.
107 * in2 will be the voltage of the 12V rail, divided by 4.
108 * temp3 will be measured using a PCB loop next the chip.
109 */
110static const u32 icy_ltc2990_meas_mode[] = {0, 3};
111
112static const struct property_entry icy_ltc2990_props[] = {
113	PROPERTY_ENTRY_U32_ARRAY("lltc,meas-mode", icy_ltc2990_meas_mode),
114	{ }
115};
116
117static const struct software_node icy_ltc2990_node = {
118	.properties = icy_ltc2990_props,
119};
120
121static int icy_probe(struct zorro_dev *z,
122		     const struct zorro_device_id *ent)
123{
124	struct icy_i2c *i2c;
125	struct i2c_algo_pcf_data *algo_data;
126	struct i2c_board_info ltc2990_info = {
127		.type		= "ltc2990",
128		.swnode		= &icy_ltc2990_node,
129	};
130
131	i2c = devm_kzalloc(&z->dev, sizeof(*i2c), GFP_KERNEL);
132	if (!i2c)
133		return -ENOMEM;
134
135	algo_data = devm_kzalloc(&z->dev, sizeof(*algo_data), GFP_KERNEL);
136	if (!algo_data)
137		return -ENOMEM;
138
139	dev_set_drvdata(&z->dev, i2c);
140	i2c->adapter.dev.parent = &z->dev;
141	i2c->adapter.owner = THIS_MODULE;
142	/* i2c->adapter.algo assigned by i2c_pcf_add_bus() */
143	i2c->adapter.algo_data = algo_data;
144	strscpy(i2c->adapter.name, "ICY I2C Zorro adapter",
145		sizeof(i2c->adapter.name));
146
147	if (!devm_request_mem_region(&z->dev,
148				     z->resource.start,
149				     4, i2c->adapter.name))
150		return -ENXIO;
151
152	/* Driver private data */
153	i2c->reg_s0 = ZTWO_VADDR(z->resource.start);
154	i2c->reg_s1 = ZTWO_VADDR(z->resource.start + 2);
155
156	algo_data->data = i2c;
157	algo_data->setpcf     = icy_pcf_setpcf;
158	algo_data->getpcf     = icy_pcf_getpcf;
159	algo_data->getown     = icy_pcf_getown;
160	algo_data->getclock   = icy_pcf_getclock;
161	algo_data->waitforpin = icy_pcf_waitforpin;
162
163	if (i2c_pcf_add_bus(&i2c->adapter)) {
164		dev_err(&z->dev, "i2c_pcf_add_bus() failed\n");
165		return -ENXIO;
166	}
167
168	dev_info(&z->dev, "ICY I2C controller at %pa, IRQ not implemented\n",
169		 &z->resource.start);
170
171	/*
172	 * The 2019 a1k.org PCBs have an LTC2990 at 0x4c, so start
173	 * it automatically once ltc2990 is modprobed.
174	 *
175	 * in0 is the voltage of the internal 5V power supply.
176	 * temp1 is the temperature inside the chip.
177	 *
178	 * See property_entry above for in1, in2, temp3.
179	 */
180	i2c->ltc2990_client = i2c_new_scanned_device(&i2c->adapter,
181						     &ltc2990_info,
182						     icy_ltc2990_addresses,
183						     NULL);
184	return 0;
185}
186
187static void icy_remove(struct zorro_dev *z)
188{
189	struct icy_i2c *i2c = dev_get_drvdata(&z->dev);
190
191	i2c_unregister_device(i2c->ltc2990_client);
192	i2c_del_adapter(&i2c->adapter);
193}
194
195static const struct zorro_device_id icy_zorro_tbl[] = {
196	{ ZORRO_ID(VMC, 15, 0), },
197	{ 0 }
198};
199
200MODULE_DEVICE_TABLE(zorro, icy_zorro_tbl);
201
202static struct zorro_driver icy_driver = {
203	.name           = "i2c-icy",
204	.id_table       = icy_zorro_tbl,
205	.probe          = icy_probe,
206	.remove         = icy_remove,
207};
208
209module_driver(icy_driver,
210	      zorro_register_driver,
211	      zorro_unregister_driver);
212
213MODULE_AUTHOR("Max Staudt <max@enpas.org>");
214MODULE_DESCRIPTION("I2C bus via PCF8584 on ICY Zorro card");
215MODULE_LICENSE("GPL v2");