Changes / enhancements to i2c indirect device auto-configuration:
— iic_search() chooses a “probe strategy” based on the "i2c-indirect-probe-strategy” property on the “iic” instance. Valid values are "smbus-quick-write”, "smbus-receive-byte”, and “none”. If no value is specified, the default is "smbus-quick-write”. — If the "i2c-indirect-device-whitelist” exists on the “iic” instance, iic_search() will first check the driver name in the cfdata_t against this list, and only allow the match/probe to move forward if the cfdata_t driver name is in the list. This is primarily to accommodate the Intel integrated memory controller neutered-i2c-thing. — If the cfdata_t specifies a wildcard address, each address of the i2c bus will be consulted. If the cfdata_t contains a nailed-down address, then we limit the bus scan to that specific address. — We explicitly skip reserved / special i2c addresses, such as the General-Call address, etc. — We introduce the notion of a “match quality” for i2c drivers. From lowest-quality to highest-quality: matched by plausible address only, matched by plausible address and poking at the bus to see if the device looks reasonable, matched by direct-config “compatible” string, matched by direct-config “driver name” string. — If the “match quality” is merely “plausible address only”, then iic_search() will use the probe strategy selected above to see if a device responds to that address.
This commit is contained in:
thorpej
parent
d2d2a14700
commit
ec79b37bf9
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@ -1,4 +1,4 @@
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/* $NetBSD: i2c.c,v 1.60 2018/06/07 05:56:18 thorpej Exp $ */
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/* $NetBSD: i2c.c,v 1.61 2018/06/07 13:30:49 thorpej Exp $ */
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/*
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* Copyright (c) 2003 Wasabi Systems, Inc.
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@ -40,7 +40,7 @@
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#endif
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: i2c.c,v 1.60 2018/06/07 05:56:18 thorpej Exp $");
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__KERNEL_RCSID(0, "$NetBSD: i2c.c,v 1.61 2018/06/07 13:30:49 thorpej Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -67,6 +67,7 @@ __KERNEL_RCSID(0, "$NetBSD: i2c.c,v 1.60 2018/06/07 05:56:18 thorpej Exp $");
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#endif
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struct iic_softc {
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device_t sc_dev;
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i2c_tag_t sc_tag;
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int sc_type;
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device_t sc_devices[I2C_MAX_ADDR + 1];
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@ -127,21 +128,160 @@ iic_print(void *aux, const char *pnp)
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return UNCONF;
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}
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static bool
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iic_is_special_address(i2c_addr_t addr)
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{
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/*
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* See: https://www.i2c-bus.org/addressing/
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*/
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/* General Call (read) / Start Byte (write) */
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if (addr == 0x00)
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return (true);
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/* CBUS Addresses */
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if (addr == 0x01)
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return (true);
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/* Reserved for Different Bus Formats */
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if (addr == 0x02)
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return (true);
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/* Reserved for future purposes */
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if (addr == 0x03)
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return (true);
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/* High Speed Master Code */
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if ((addr & 0x7c) == 0x04)
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return (true);
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/* 10-bit Slave Addressing prefix */
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if ((addr & 0x7c) == 0x78)
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return (true);
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/* Reserved for future purposes */
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if ((addr & 0x7c) == 0x7c)
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return (true);
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return (false);
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}
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static int
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iic_probe_none(struct iic_softc *sc,
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const struct i2c_attach_args *ia, int flags)
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{
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return (0);
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}
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static int
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iic_probe_smbus_quick_write(struct iic_softc *sc,
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const struct i2c_attach_args *ia, int flags)
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{
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int error;
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if ((error = iic_acquire_bus(ia->ia_tag, flags)) == 0) {
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error = iic_smbus_quick_write(ia->ia_tag, ia->ia_addr, flags);
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}
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(void) iic_release_bus(ia->ia_tag, flags);
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return (error);
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}
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static int
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iic_probe_smbus_receive_byte(struct iic_softc *sc,
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const struct i2c_attach_args *ia, int flags)
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{
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int error;
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if ((error = iic_acquire_bus(ia->ia_tag, flags)) == 0) {
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uint8_t dummy;
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error = iic_smbus_receive_byte(ia->ia_tag, ia->ia_addr,
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&dummy, flags);
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}
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(void) iic_release_bus(ia->ia_tag, flags);
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return (error);
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}
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static bool
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iic_indirect_driver_is_whitelisted(struct iic_softc *sc, cfdata_t cf)
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{
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prop_object_iterator_t iter;
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prop_array_t whitelist;
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prop_string_t pstr;
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prop_type_t ptype;
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bool rv = false;
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whitelist = prop_dictionary_get(device_properties(sc->sc_dev),
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I2C_PROP_INDIRECT_DEVICE_WHITELIST);
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if (whitelist == NULL) {
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/* No whitelist -> everything allowed */
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return (true);
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}
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if ((ptype = prop_object_type(whitelist)) != PROP_TYPE_ARRAY) {
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aprint_error_dev(sc->sc_dev,
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"invalid property type (%d) for '%s'; must be array (%d)\n",
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ptype, I2C_PROP_INDIRECT_DEVICE_WHITELIST, PROP_TYPE_ARRAY);
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return (false);
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}
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iter = prop_array_iterator(whitelist);
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while ((pstr = prop_object_iterator_next(iter)) != NULL) {
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if (prop_string_equals_cstring(pstr, cf->cf_name)) {
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rv = true;
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break;
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}
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}
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prop_object_iterator_release(iter);
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return (rv);
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}
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static int
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iic_search(device_t parent, cfdata_t cf, const int *ldesc, void *aux)
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{
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struct iic_softc *sc = device_private(parent);
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struct i2c_attach_args ia;
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int (*probe_func)(struct iic_softc *,
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const struct i2c_attach_args *, int);
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prop_string_t pstr;
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i2c_addr_t first_addr, last_addr;
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/*
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* I2C doesn't have any regular probing capability. If we
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* encounter a cfdata with a wild-carded address or a wild-
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* carded parent spec, we skip them because they can only
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* be used for direct-coniguration.
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* Before we do any more work, consult the allowed-driver
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* white-list for this bus (if any).
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*/
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if (cf->cf_loc[IICCF_ADDR] == IICCF_ADDR_DEFAULT ||
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cf->cf_pspec->cfp_unit == DVUNIT_ANY)
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return 0;
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if (iic_indirect_driver_is_whitelisted(sc, cf) == false)
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return (0);
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/* default to "quick write". */
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probe_func = iic_probe_smbus_quick_write;
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pstr = prop_dictionary_get(device_properties(sc->sc_dev),
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I2C_PROP_INDIRECT_PROBE_STRATEGY);
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if (pstr == NULL) {
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/* Use the default. */
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} else if (prop_string_equals_cstring(pstr,
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I2C_PROBE_STRATEGY_QUICK_WRITE)) {
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probe_func = iic_probe_smbus_quick_write;
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} else if (prop_string_equals_cstring(pstr,
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I2C_PROBE_STRATEGY_RECEIVE_BYTE)) {
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probe_func = iic_probe_smbus_receive_byte;
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} else if (prop_string_equals_cstring(pstr,
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I2C_PROBE_STRATEGY_NONE)) {
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probe_func = iic_probe_none;
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} else {
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aprint_error_dev(sc->sc_dev,
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"unknown probe strategy '%s'; defaulting to '%s'\n",
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prop_string_cstring_nocopy(pstr),
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I2C_PROBE_STRATEGY_QUICK_WRITE);
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/* Use the default. */
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}
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ia.ia_tag = sc->sc_tag;
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ia.ia_size = cf->cf_loc[IICCF_SIZE];
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@ -152,16 +292,74 @@ iic_search(device_t parent, cfdata_t cf, const int *ldesc, void *aux)
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ia.ia_compat = NULL;
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ia.ia_prop = NULL;
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for (ia.ia_addr = 0; ia.ia_addr <= I2C_MAX_ADDR; ia.ia_addr++) {
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if (cf->cf_loc[IICCF_ADDR] == IICCF_ADDR_DEFAULT) {
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/*
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* This particular config directive has
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* wildcarded the address, so we will
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* scan the entire bus for it.
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*/
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first_addr = 0;
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last_addr = I2C_MAX_ADDR;
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} else {
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/*
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* This config directive hard-wires the i2c
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* bus address for the device, so there is
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* no need to go poking around at any other
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* addresses.
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*/
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if (cf->cf_loc[IICCF_ADDR] < 0 ||
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cf->cf_loc[IICCF_ADDR] > I2C_MAX_ADDR) {
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/* Invalid config directive! */
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return (0);
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}
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first_addr = last_addr = cf->cf_loc[IICCF_ADDR];
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}
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for (ia.ia_addr = first_addr; ia.ia_addr <= last_addr; ia.ia_addr++) {
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int error, match_result;
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/*
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* Skip I2C addresses that are reserved for
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* special purposes.
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*/
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if (iic_is_special_address(ia.ia_addr))
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continue;
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/*
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* Skip addresses where a device is already attached.
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*/
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if (sc->sc_devices[ia.ia_addr] != NULL)
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continue;
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if (cf->cf_loc[IICCF_ADDR] != ia.ia_addr)
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/*
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* Call the "match" routine for the device. If that
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* returns success, then call the probe strategy
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* function.
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*
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* We do it in this order because i2c devices tend
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* to be found at a small number of possible addresses
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* (e.g. read-time clocks that are only ever found at
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* 0x68). This gives the driver a chance to skip any
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* address that are not valid for the device, saving
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* us from having to poke at the bus to see if anything
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* is there.
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*/
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match_result = config_match(parent, cf, &ia);
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if (match_result <= 0)
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continue;
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if (config_match(parent, cf, &ia) > 0)
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sc->sc_devices[ia.ia_addr] =
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config_attach(parent, cf, &ia, iic_print);
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/*
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* If the quality of the match by the driver was low
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* (i.e. matched on being a valid address only, didn't
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* perform any hardware probe), invoke our probe routine
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* to see if it looks like something is really there.
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*/
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if (match_result == I2C_MATCH_ADDRESS_ONLY &&
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(error = (*probe_func)(sc, &ia, I2C_F_POLL)) != 0)
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continue;
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sc->sc_devices[ia.ia_addr] =
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config_attach(parent, cf, &ia, iic_print);
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}
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return 0;
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@ -209,6 +407,7 @@ iic_attach(device_t parent, device_t self, void *aux)
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aprint_naive("\n");
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aprint_normal(": I2C bus\n");
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sc->sc_dev = self;
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sc->sc_tag = iba->iba_tag;
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sc->sc_type = iba->iba_type;
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ic = sc->sc_tag;
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@ -1,4 +1,4 @@
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/* $NetBSD: i2cvar.h,v 1.12 2018/06/07 05:56:18 thorpej Exp $ */
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/* $NetBSD: i2cvar.h,v 1.13 2018/06/07 13:30:49 thorpej Exp $ */
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/*
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* Copyright (c) 2003 Wasabi Systems, Inc.
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@ -49,6 +49,20 @@
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#define I2C_F_POLL 0x08 /* poll, don't sleep */
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#define I2C_F_PEC 0x10 /* smbus packet error checking */
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/* i2c bus instance properties */
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#define I2C_PROP_INDIRECT_PROBE_STRATEGY \
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"i2c-indirect-probe-strategy"
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#define I2C_PROBE_STRATEGY_QUICK_WRITE \
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"smbus-quick-write"
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#define I2C_PROBE_STRATEGY_RECEIVE_BYTE \
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"smbus-receive-byte"
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#define I2C_PROBE_STRATEGY_NONE \
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"none"
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#define I2C_PROP_INDIRECT_DEVICE_WHITELIST \
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"i2c-indirect-device-whitelist"
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/* value is a prop_array of prop_strings */
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struct ic_intr_list {
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LIST_ENTRY(ic_intr_list) il_next;
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int (*il_intr)(void *);
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@ -147,6 +161,23 @@ struct i2c_attach_args {
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int iicbus_print(void *, const char *);
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int iic_compat_match(struct i2c_attach_args*, const char **);
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/*
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* Constants to indicate the quality of a match made by a driver's
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* match routine, from lowest to higest:
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*
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* -- Address only; no other checks were made.
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*
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* -- Address + device probed and recognized.
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*
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* -- Direct-config match by "compatible" string.
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*
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* -- Direct-config match by specific driver name.
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*/
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#define I2C_MATCH_ADDRESS_ONLY 1
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#define I2C_MATCH_ADDRESS_AND_PROBE 2
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#define I2C_MATCH_DIRECT_COMPATIBLE 10
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#define I2C_MATCH_DIRECT_SPECIFIC 50
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#ifdef _I2C_PRIVATE
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/*
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* Macros used internally by the i2c framework.
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