xref: /freebsd/sys/dev/iicbus/mux/ltc430x.c (revision cc1a53bc1aea0675d64e9547cdca241612906592)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
31 #include "opt_platform.h"
32 
33 #include <sys/param.h>
34 #include <sys/bus.h>
35 #include <sys/kernel.h>
36 #include <sys/module.h>
37 #include <sys/systm.h>
38 
39 #include <dev/iicbus/iicbus.h>
40 #include <dev/iicbus/iiconf.h>
41 #include "iicbus_if.h"
42 #include "iicmux_if.h"
43 
44 static struct chip_info {
45 	const char 	*partname;
46 	const char	*description;
47 	int		numchannels;
48 } chip_infos[] = {
49 	{"ltc4305", "LTC4305 I2C Mux", 2},
50 	{"ltc4306", "LTC4306 I2C Mux", 4},
51 };
52 #define CHIP_NONE	(-1)
53 #define	CHIP_LTC4305	0
54 #define	CHIP_LTC4306	1
55 
56 #ifdef FDT
57 #include <dev/ofw/ofw_bus.h>
58 #include <dev/ofw/ofw_bus_subr.h>
59 #include <dev/ofw/openfirm.h>
60 
61 static struct ofw_compat_data compat_data[] = {
62 	{"lltc,ltc4305",  CHIP_LTC4305},
63 	{"lltc,ltc4306",  CHIP_LTC4306},
64 	{NULL,            CHIP_NONE}
65 };
66 IICBUS_FDT_PNP_INFO(compat_data);
67 #endif
68 
69 #include <dev/iicbus/mux/iicmux.h>
70 
71 struct ltc430x_softc {
72 	struct iicmux_softc mux;
73 	bool idle_disconnect;
74 };
75 
76 /*
77  * The datasheet doesn't name the registers, it calls them control register 0-3.
78  */
79 #define	LTC430X_CTLREG_0	0
80 #define	LTC430X_CTLREG_1	1
81 #define	LTC430X_CTLREG_2	2
82 #define	  LTC430X_CR2_ENABLE_MW	  (1u << 3) /* Enable mass write address. */
83 #define	LTC430X_CTLREG_3	3
84 
85 static int
86 ltc430x_bus_select(device_t dev, int busidx, struct iic_reqbus_data *rd)
87 {
88 	struct ltc430x_softc *sc = device_get_softc(dev);
89 	uint8_t busbits;
90 
91 	/*
92 	 * The iicmux caller ensures busidx is between 0 and the number of buses
93 	 * we passed to iicmux_init_softc(), no need for validation here.  If
94 	 * the fdt data has the idle_disconnect property we idle the bus by
95 	 * selecting no downstream buses, otherwise we just leave the current
96 	 * bus active.  The upper bits of control register 3 activate the
97 	 * downstream buses; bit 7 is the first bus, bit 6 the second, etc.
98 	 */
99 	if (busidx == IICMUX_SELECT_IDLE) {
100 		if (sc->idle_disconnect)
101 			busbits = 0;
102 		else
103 			return (0);
104 	} else {
105 		busbits = 1u << (7 - busidx);
106 	}
107 
108 	/*
109 	 * We have to add the IIC_RECURSIVE flag because the iicmux core has
110 	 * already reserved the bus for us, and iicdev_writeto() is going to try
111 	 * to reserve it again, which is allowed with the recursive flag.
112 	 */
113 	return (iicdev_writeto(dev, LTC430X_CTLREG_3, &busbits, sizeof(busbits),
114 	    rd->flags | IIC_RECURSIVE));
115 }
116 
117 static int
118 ltc430x_find_chiptype(device_t dev)
119 {
120 #ifdef FDT
121 	return (ofw_bus_search_compatible(dev, compat_data)->ocd_data);
122 #else
123 	const char *type;
124 	int i;
125 
126 	if (resource_string_value(device_get_name(dev), device_get_unit(dev),
127 	    "chip_type", &type) == 0) {
128 		for (i = 0; i < nitems(chip_infos); ++i) {
129 			if (strcasecmp(type, chip_infos[i].partname) == 0) {
130 				return (i);
131 			}
132 		}
133 	}
134 	return (CHIP_NONE);
135 #endif
136 }
137 
138 static int
139 ltc430x_probe(device_t dev)
140 {
141 	int type;
142 
143 #ifdef FDT
144 	if (!ofw_bus_status_okay(dev))
145 		return (ENXIO);
146 #endif
147 
148 	type = ltc430x_find_chiptype(dev);
149 	if (type == CHIP_NONE)
150 		return (ENXIO);
151 
152 	device_set_desc(dev, chip_infos[type].description);
153 
154 	return (BUS_PROBE_DEFAULT);
155 }
156 
157 static int
158 ltc430x_attach(device_t dev)
159 {
160 	struct ltc430x_softc *sc __unused;
161 	int chip, err, numchan, val;
162 	uint8_t busbits, ctlreg2;
163 
164 	sc = device_get_softc(dev);
165 
166 	busbits = 0;
167 	ctlreg2 = LTC430X_CR2_ENABLE_MW;
168 
169 	/*
170 	 * Check for the idle-disconnect and ctlreg2 options, first in FDT data,
171 	 * then allow them to be overriden by hints data.
172 	 */
173 #ifdef FDT
174 	phandle_t node;
175 
176 	node = ofw_bus_get_node(dev);
177 	sc->idle_disconnect = OF_hasprop(node, "i2c-mux-idle-disconnect");
178 
179 	if (OF_getprop(node, "freebsd,ctlreg2", &val, sizeof(val)) > 0) {
180 		ctlreg2 = val;
181 	}
182 #endif
183 
184 	if (resource_int_value(device_get_name(dev), device_get_unit(dev),
185 	    "idle_disconnect", &val) == 0) {
186 		sc->idle_disconnect = val;
187 	}
188 
189 	if (resource_int_value(device_get_name(dev), device_get_unit(dev),
190 	    "ctlreg2", &val) == 0) {
191 		ctlreg2 = val;
192 	}
193 
194 	/* We found the chip type when probing, so now it "can't fail". */
195 	if ((chip = ltc430x_find_chiptype(dev)) == CHIP_NONE) {
196 		device_printf(dev, "impossible: can't identify chip type\n");
197 		return (ENXIO);
198 	}
199 	numchan = chip_infos[chip].numchannels;
200 
201 	/* Set control reg 2 with configured (or default) values. */
202 	iicdev_writeto(dev, LTC430X_CTLREG_2, &ctlreg2, sizeof(ctlreg2),
203 	    IIC_WAIT);
204 
205 	/* If configured for idle-disconnect, ensure we start disconnected. */
206 	if (sc->idle_disconnect) {
207 		iicdev_writeto(dev, LTC430X_CTLREG_3, &busbits, sizeof(busbits),
208 		    IIC_WAIT);
209 	}
210 
211 	/*
212 	 * Invoke the iicmux framework's attach code, and if it succeeds, invoke
213 	 * the probe and attach code of any child iicbus instances it added.
214 	 */
215 	if ((err = iicmux_attach(dev, device_get_parent(dev), numchan)) == 0)
216 		bus_generic_attach(dev);
217 
218 	return (err);
219 }
220 
221 static int
222 ltc430x_detach(device_t dev)
223 {
224 	int err;
225 
226 	if ((err = iicmux_detach(dev)) != 0)
227 		return (err);
228 
229 	return (0);
230 }
231 
232 static device_method_t ltc430x_methods[] = {
233 	/* device methods */
234 	DEVMETHOD(device_probe,			ltc430x_probe),
235 	DEVMETHOD(device_attach,		ltc430x_attach),
236 	DEVMETHOD(device_detach,		ltc430x_detach),
237 
238 	/* iicmux methods */
239 	DEVMETHOD(iicmux_bus_select,		ltc430x_bus_select),
240 
241 	DEVMETHOD_END
242 };
243 
244 DEFINE_CLASS_1(ltc430x, ltc430x_driver, ltc430x_methods,
245     sizeof(struct ltc430x_softc), iicmux_driver);
246 DRIVER_MODULE(ltc430x, iicbus, ltc430x_driver, 0, 0);
247 
248 #ifdef FDT
249 DRIVER_MODULE(ofw_iicbus, ltc430x, ofw_iicbus_driver, 0, 0);
250 #else
251 DRIVER_MODULE(iicbus, ltc430x, iicbus_driver, 0, 0);
252 #endif
253 
254 MODULE_DEPEND(ltc430x, iicmux, 1, 1, 1);
255 MODULE_DEPEND(ltc430x, iicbus, 1, 1, 1);
256 
257