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 fwnode_handle *ltc2990_fwnode;
58	struct i2c_client *ltc2990_client;
59};
60
61/*
62 * Functions called by i2c-algo-pcf
63 */
64static void icy_pcf_setpcf(void *data, int ctl, int val)
65{
66	struct icy_i2c *i2c = (struct icy_i2c *)data;
67
68	u8 __iomem *address = ctl ? i2c->reg_s1 : i2c->reg_s0;
69
70	z_writeb(val, address);
71}
72
73static int icy_pcf_getpcf(void *data, int ctl)
74{
75	struct icy_i2c *i2c = (struct icy_i2c *)data;
76
77	u8 __iomem *address = ctl ? i2c->reg_s1 : i2c->reg_s0;
78
79	return z_readb(address);
80}
81
82static int icy_pcf_getown(void *data)
83{
84	return 0x55;
85}
86
87static int icy_pcf_getclock(void *data)
88{
89	return 0x1c;
90}
91
92static void icy_pcf_waitforpin(void *data)
93{
94	usleep_range(50, 150);
95}
96
97/*
98 * Main i2c-icy part
99 */
100static unsigned short const icy_ltc2990_addresses[] = {
101	0x4c, 0x4d, 0x4e, 0x4f, I2C_CLIENT_END
102};
103
104/*
105 * Additional sensors exposed once this property is applied:
106 *
107 * in1 will be the voltage of the 5V rail, divided by 2.
108 * in2 will be the voltage of the 12V rail, divided by 4.
109 * temp3 will be measured using a PCB loop next the chip.
110 */
111static const u32 icy_ltc2990_meas_mode[] = {0, 3};
112
113static const struct property_entry icy_ltc2990_props[] = {
114	PROPERTY_ENTRY_U32_ARRAY("lltc,meas-mode", icy_ltc2990_meas_mode),
115	{ }
116};
117
118static int icy_probe(struct zorro_dev *z,
119		     const struct zorro_device_id *ent)
120{
121	struct icy_i2c *i2c;
122	struct i2c_algo_pcf_data *algo_data;
123	struct fwnode_handle *new_fwnode;
124	struct i2c_board_info ltc2990_info = {
125		.type		= "ltc2990",
126	};
127
128	i2c = devm_kzalloc(&z->dev, sizeof(*i2c), GFP_KERNEL);
129	if (!i2c)
130		return -ENOMEM;
131
132	algo_data = devm_kzalloc(&z->dev, sizeof(*algo_data), GFP_KERNEL);
133	if (!algo_data)
134		return -ENOMEM;
135
136	dev_set_drvdata(&z->dev, i2c);
137	i2c->adapter.dev.parent = &z->dev;
138	i2c->adapter.owner = THIS_MODULE;
139	/* i2c->adapter.algo assigned by i2c_pcf_add_bus() */
140	i2c->adapter.algo_data = algo_data;
141	strlcpy(i2c->adapter.name, "ICY I2C Zorro adapter",
142		sizeof(i2c->adapter.name));
143
144	if (!devm_request_mem_region(&z->dev,
145				     z->resource.start,
146				     4, i2c->adapter.name))
147		return -ENXIO;
148
149	/* Driver private data */
150	i2c->reg_s0 = ZTWO_VADDR(z->resource.start);
151	i2c->reg_s1 = ZTWO_VADDR(z->resource.start + 2);
152
153	algo_data->data = i2c;
154	algo_data->setpcf     = icy_pcf_setpcf;
155	algo_data->getpcf     = icy_pcf_getpcf;
156	algo_data->getown     = icy_pcf_getown;
157	algo_data->getclock   = icy_pcf_getclock;
158	algo_data->waitforpin = icy_pcf_waitforpin;
159
160	if (i2c_pcf_add_bus(&i2c->adapter)) {
161		dev_err(&z->dev, "i2c_pcf_add_bus() failed\n");
162		return -ENXIO;
163	}
164
165	dev_info(&z->dev, "ICY I2C controller at %pa, IRQ not implemented\n",
166		 &z->resource.start);
167
168	/*
169	 * The 2019 a1k.org PCBs have an LTC2990 at 0x4c, so start
170	 * it automatically once ltc2990 is modprobed.
171	 *
172	 * in0 is the voltage of the internal 5V power supply.
173	 * temp1 is the temperature inside the chip.
174	 *
175	 * See property_entry above for in1, in2, temp3.
176	 */
177	new_fwnode = fwnode_create_software_node(icy_ltc2990_props, NULL);
178	if (IS_ERR(new_fwnode)) {
179		dev_info(&z->dev, "Failed to create fwnode for LTC2990, error: %ld\n",
180			 PTR_ERR(new_fwnode));
181	} else {
182		/*
183		 * Store the fwnode so we can destroy it on .remove().
184		 * Only store it on success, as fwnode_remove_software_node()
185		 * is NULL safe, but not PTR_ERR safe.
186		 */
187		i2c->ltc2990_fwnode = new_fwnode;
188		ltc2990_info.fwnode = new_fwnode;
189
190		i2c->ltc2990_client =
191			i2c_new_scanned_device(&i2c->adapter,
192					       &ltc2990_info,
193					       icy_ltc2990_addresses,
194					       NULL);
195	}
196
197	return 0;
198}
199
200static void icy_remove(struct zorro_dev *z)
201{
202	struct icy_i2c *i2c = dev_get_drvdata(&z->dev);
203
204	i2c_unregister_device(i2c->ltc2990_client);
205	fwnode_remove_software_node(i2c->ltc2990_fwnode);
206
207	i2c_del_adapter(&i2c->adapter);
208}
209
210static const struct zorro_device_id icy_zorro_tbl[] = {
211	{ ZORRO_ID(VMC, 15, 0), },
212	{ 0 }
213};
214
215MODULE_DEVICE_TABLE(zorro, icy_zorro_tbl);
216
217static struct zorro_driver icy_driver = {
218	.name           = "i2c-icy",
219	.id_table       = icy_zorro_tbl,
220	.probe          = icy_probe,
221	.remove         = icy_remove,
222};
223
224module_driver(icy_driver,
225	      zorro_register_driver,
226	      zorro_unregister_driver);
227
228MODULE_AUTHOR("Max Staudt <max@enpas.org>");
229MODULE_DESCRIPTION("I2C bus via PCF8584 on ICY Zorro card");
230MODULE_LICENSE("GPL v2");
231