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/amigaints.h>
47 #include <linux/zorro.h>
48
49 #include "../algos/i2c-algo-pcf.h"
50
51 struct icy_i2c {
52 struct i2c_adapter adapter;
53
54 void __iomem *reg_s0;
55 void __iomem *reg_s1;
56 struct fwnode_handle *ltc2990_fwnode;
57 struct i2c_client *ltc2990_client;
58 };
59
60 /*
61 * Functions called by i2c-algo-pcf
62 */
icy_pcf_setpcf(void * data,int ctl,int val)63 static 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
icy_pcf_getpcf(void * data,int ctl)72 static 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
icy_pcf_getown(void * data)81 static int icy_pcf_getown(void *data)
82 {
83 return 0x55;
84 }
85
icy_pcf_getclock(void * data)86 static int icy_pcf_getclock(void *data)
87 {
88 return 0x1c;
89 }
90
icy_pcf_waitforpin(void * data)91 static void icy_pcf_waitforpin(void *data)
92 {
93 usleep_range(50, 150);
94 }
95
96 /*
97 * Main i2c-icy part
98 */
99 static 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 */
110 static const u32 icy_ltc2990_meas_mode[] = {0, 3};
111
112 static const struct property_entry icy_ltc2990_props[] = {
113 PROPERTY_ENTRY_U32_ARRAY("lltc,meas-mode", icy_ltc2990_meas_mode),
114 { }
115 };
116
icy_probe(struct zorro_dev * z,const struct zorro_device_id * ent)117 static int icy_probe(struct zorro_dev *z,
118 const struct zorro_device_id *ent)
119 {
120 struct icy_i2c *i2c;
121 struct i2c_algo_pcf_data *algo_data;
122 struct fwnode_handle *new_fwnode;
123 struct i2c_board_info ltc2990_info = {
124 .type = "ltc2990",
125 .addr = 0x4c,
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_probed_device(&i2c->adapter,
192 <c2990_info,
193 icy_ltc2990_addresses,
194 NULL);
195 }
196
197 return 0;
198 }
199
icy_remove(struct zorro_dev * z)200 static 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
210 static const struct zorro_device_id icy_zorro_tbl[] = {
211 { ZORRO_ID(VMC, 15, 0), },
212 { 0 }
213 };
214
215 MODULE_DEVICE_TABLE(zorro, icy_zorro_tbl);
216
217 static 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
224 module_driver(icy_driver,
225 zorro_register_driver,
226 zorro_unregister_driver);
227
228 MODULE_AUTHOR("Max Staudt <max@enpas.org>");
229 MODULE_DESCRIPTION("I2C bus via PCF8584 on ICY Zorro card");
230 MODULE_LICENSE("GPL v2");
231
