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#include "opt_platform.h"
30
31#include <sys/param.h>
32#include <sys/bus.h>
33#include <sys/kernel.h>
34#include <sys/module.h>
35#include <sys/systm.h>
36
37#include <dev/iicbus/iicbus.h>
38#include <dev/iicbus/iiconf.h>
39#include "iicbus_if.h"
40#include "iicmux_if.h"
41
42static struct chip_info {
43	const char 	*partname;
44	const char	*description;
45	int		numchannels;
46} chip_infos[] = {
47	{"ltc4305", "LTC4305 I2C Mux", 2},
48	{"ltc4306", "LTC4306 I2C Mux", 4},
49};
50#define CHIP_NONE	(-1)
51#define	CHIP_LTC4305	0
52#define	CHIP_LTC4306	1
53
54#ifdef FDT
55#include <dev/ofw/ofw_bus.h>
56#include <dev/ofw/ofw_bus_subr.h>
57#include <dev/ofw/openfirm.h>
58
59static struct ofw_compat_data compat_data[] = {
60	{"lltc,ltc4305",  CHIP_LTC4305},
61	{"lltc,ltc4306",  CHIP_LTC4306},
62	{NULL,            CHIP_NONE}
63};
64IICBUS_FDT_PNP_INFO(compat_data);
65#endif
66
67#include <dev/iicbus/mux/iicmux.h>
68
69struct ltc430x_softc {
70	struct iicmux_softc mux;
71	bool idle_disconnect;
72};
73
74/*
75 * The datasheet doesn't name the registers, it calls them control register 0-3.
76 */
77#define	LTC430X_CTLREG_0	0
78#define	LTC430X_CTLREG_1	1
79#define	LTC430X_CTLREG_2	2
80#define	  LTC430X_CR2_ENABLE_MW	  (1u << 3) /* Enable mass write address. */
81#define	LTC430X_CTLREG_3	3
82
83static int
84ltc430x_bus_select(device_t dev, int busidx, struct iic_reqbus_data *rd)
85{
86	struct ltc430x_softc *sc = device_get_softc(dev);
87	uint8_t busbits;
88
89	/*
90	 * The iicmux caller ensures busidx is between 0 and the number of buses
91	 * we passed to iicmux_init_softc(), no need for validation here.  If
92	 * the fdt data has the idle_disconnect property we idle the bus by
93	 * selecting no downstream buses, otherwise we just leave the current
94	 * bus active.  The upper bits of control register 3 activate the
95	 * downstream buses; bit 7 is the first bus, bit 6 the second, etc.
96	 */
97	if (busidx == IICMUX_SELECT_IDLE) {
98		if (sc->idle_disconnect)
99			busbits = 0;
100		else
101			return (0);
102	} else {
103		busbits = 1u << (7 - busidx);
104	}
105
106	/*
107	 * We have to add the IIC_RECURSIVE flag because the iicmux core has
108	 * already reserved the bus for us, and iicdev_writeto() is going to try
109	 * to reserve it again, which is allowed with the recursive flag.
110	 */
111	return (iicdev_writeto(dev, LTC430X_CTLREG_3, &busbits, sizeof(busbits),
112	    rd->flags | IIC_RECURSIVE));
113}
114
115static int
116ltc430x_find_chiptype(device_t dev)
117{
118#ifdef FDT
119	return (ofw_bus_search_compatible(dev, compat_data)->ocd_data);
120#else
121	const char *type;
122	int i;
123
124	if (resource_string_value(device_get_name(dev), device_get_unit(dev),
125	    "chip_type", &type) == 0) {
126		for (i = 0; i < nitems(chip_infos); ++i) {
127			if (strcasecmp(type, chip_infos[i].partname) == 0) {
128				return (i);
129			}
130		}
131	}
132	return (CHIP_NONE);
133#endif
134}
135
136static int
137ltc430x_probe(device_t dev)
138{
139	int type;
140
141#ifdef FDT
142	if (!ofw_bus_status_okay(dev))
143		return (ENXIO);
144#endif
145
146	type = ltc430x_find_chiptype(dev);
147	if (type == CHIP_NONE)
148		return (ENXIO);
149
150	device_set_desc(dev, chip_infos[type].description);
151
152	return (BUS_PROBE_DEFAULT);
153}
154
155static int
156ltc430x_attach(device_t dev)
157{
158	struct ltc430x_softc *sc __unused;
159	int chip, err, numchan, val;
160	uint8_t busbits, ctlreg2;
161
162	sc = device_get_softc(dev);
163
164	busbits = 0;
165	ctlreg2 = LTC430X_CR2_ENABLE_MW;
166
167	/*
168	 * Check for the idle-disconnect and ctlreg2 options, first in FDT data,
169	 * then allow them to be overridden by hints data.
170	 */
171#ifdef FDT
172	phandle_t node;
173
174	node = ofw_bus_get_node(dev);
175	sc->idle_disconnect = OF_hasprop(node, "i2c-mux-idle-disconnect");
176
177	if (OF_getprop(node, "freebsd,ctlreg2", &val, sizeof(val)) > 0) {
178		ctlreg2 = val;
179	}
180#endif
181
182	if (resource_int_value(device_get_name(dev), device_get_unit(dev),
183	    "idle_disconnect", &val) == 0) {
184		sc->idle_disconnect = val;
185	}
186
187	if (resource_int_value(device_get_name(dev), device_get_unit(dev),
188	    "ctlreg2", &val) == 0) {
189		ctlreg2 = val;
190	}
191
192	/* We found the chip type when probing, so now it "can't fail". */
193	if ((chip = ltc430x_find_chiptype(dev)) == CHIP_NONE) {
194		device_printf(dev, "impossible: can't identify chip type\n");
195		return (ENXIO);
196	}
197	numchan = chip_infos[chip].numchannels;
198
199	/* Set control reg 2 with configured (or default) values. */
200	iicdev_writeto(dev, LTC430X_CTLREG_2, &ctlreg2, sizeof(ctlreg2),
201	    IIC_WAIT);
202
203	/* If configured for idle-disconnect, ensure we start disconnected. */
204	if (sc->idle_disconnect) {
205		iicdev_writeto(dev, LTC430X_CTLREG_3, &busbits, sizeof(busbits),
206		    IIC_WAIT);
207	}
208
209	/*
210	 * Invoke the iicmux framework's attach code, and if it succeeds, invoke
211	 * the probe and attach code of any child iicbus instances it added.
212	 */
213	if ((err = iicmux_attach(dev, device_get_parent(dev), numchan)) == 0)
214		bus_generic_attach(dev);
215
216	return (err);
217}
218
219static int
220ltc430x_detach(device_t dev)
221{
222	int err;
223
224	if ((err = iicmux_detach(dev)) != 0)
225		return (err);
226
227	return (0);
228}
229
230static device_method_t ltc430x_methods[] = {
231	/* device methods */
232	DEVMETHOD(device_probe,			ltc430x_probe),
233	DEVMETHOD(device_attach,		ltc430x_attach),
234	DEVMETHOD(device_detach,		ltc430x_detach),
235
236	/* iicmux methods */
237	DEVMETHOD(iicmux_bus_select,		ltc430x_bus_select),
238
239	DEVMETHOD_END
240};
241
242DEFINE_CLASS_1(ltc430x, ltc430x_driver, ltc430x_methods,
243    sizeof(struct ltc430x_softc), iicmux_driver);
244DRIVER_MODULE(ltc430x, iicbus, ltc430x_driver, 0, 0);
245
246#ifdef FDT
247DRIVER_MODULE(ofw_iicbus, ltc430x, ofw_iicbus_driver, 0, 0);
248#else
249DRIVER_MODULE(iicbus, ltc430x, iicbus_driver, 0, 0);
250#endif
251
252MODULE_DEPEND(ltc430x, iicmux, 1, 1, 1);
253MODULE_DEPEND(ltc430x, iicbus, 1, 1, 1);
254
255