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From:
Tobias Heider <tobias.heider@stusta.de>
Subject:
Re: scmi(4): add mbox transport and perf protocol
To:
Mark Kettenis <mark.kettenis@xs4all.nl>
Cc:
tech@openbsd.org, kettenis@openbsd.org, patrick@openbsd.org, landry@openbsd.org
Date:
Wed, 20 Nov 2024 22:05:45 +0100

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On Tue, Nov 19, 2024 at 10:30:58PM GMT, Mark Kettenis wrote:
> > Date: Tue, 19 Nov 2024 22:03:01 +0100
> > From: Mark Kettenis <mark.kettenis@xs4all.nl>
> > 
> > > Date: Tue, 19 Nov 2024 14:20:12 +0100
> > > From: Mark Kettenis <mark.kettenis@xs4all.nl>
> > > 
> > > > Date: Mon, 18 Nov 2024 01:01:11 +0100
> > > > From: Tobias Heider <tobias.heider@stusta.de>
> > > > 
> > > > Here is the promised diff to get scmi for cpu frequency management
> > > > working on the Snapdragon X Elite.  Roughly speaking this adds two
> > > > big new features: mailbox transport and the scmi perf protocol.
> > > > 
> > > > Mailbox transport is very similar to smc which we already support.
> > > > Messages are written to a shared memory region, instead of an SMC call we
> > > > use a mailbox doorbell to notify the platform that our request is ready.
> > > > On X Elites this is done using the CPUCP mailbox which we support via
> > > > qccpucp(4). The attach function for the mbox transport is deferred to make
> > > > sure our mailbox driver is available when we need it.
> > > > There are a lot of possible optimization here, instead of polling we could
> > > > use mailbox interrupts and for PERFORMANCE_LEVEL_GET we probably want to
> > > > switch to using a fast channel at some point.
> > > > 
> > > > The perf protocol allows us to read and set the performance level of our
> > > > performance domains. On the X Elite we have 3 domains, each spanning 4 cpu
> > > > cores. This patch adds sensors to expose the current frequency and power
> > > > consumption for each domain. It is a bit pointless since the level doesn't
> > > > really change currently. Eventually we probably want to hook this up to
> > > > cpu(4) to expose it to apm(8).
> > > > 
> > > > The output on my T14s looks like this:
> > > > $ sysctl | grep scmi                                                   
> > > > hw.sensors.scmi0.power0=0.22 W
> > > > hw.sensors.scmi0.power1=0.29 W
> > > > hw.sensors.scmi0.power2=0.31 W
> > > > hw.sensors.scmi0.frequency0=2976000000.00 Hz
> > > > hw.sensors.scmi0.frequency1=3417600000.00 Hz
> > > > hw.sensors.scmi0.frequency2=3417600000.00 Hz
> > > > 
> > > > Test feedback and reviews welcome. I don't have a machine using scmi-smc or
> > > > the clock protocol so I'd appreciate if someone could test those too.
> > > 
> > > A first drive-by review.  I need to test this on some hardware that
> > > implements scmi-smc before I give an ok.  But it basically looks ok.
> > 
> > The rk3588 isn't happy with this.  I'll investigate...
> 
> Turns out to be a simple typo:
> 
> > > > +
> > > > +	if (OF_is_compatible(faa->fa_node, "arm,scmi-scm")) {
> > > > +		scmi_attach_smc(sc, faa);
> 
> Should be "arm,scmi-smc".

Here is a new version with all the feedback incorporated.
Tests look good, works on X Elite, still work on Rockchip.

ok?

diff a921796a245d04e3f9e9aeb92b328e0f67f5f697 1aba915c8fcaa5bd088fa5d0bf872ef48b3bd3eb
commit - a921796a245d04e3f9e9aeb92b328e0f67f5f697
commit + 1aba915c8fcaa5bd088fa5d0bf872ef48b3bd3eb
blob - 5c567e567920508ecda4cc718168b85cc356898b
blob + f7b1bf68a50fae33b840a317d0311e9d2143a31e
--- sys/dev/fdt/scmi.c
+++ sys/dev/fdt/scmi.c
@@ -2,6 +2,7 @@
 
 /*
  * Copyright (c) 2023 Mark Kettenis <kettenis@openbsd.org>
+ * Copyright (c) 2024 Tobias Heider <tobhe@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -19,12 +20,16 @@
 #include <sys/param.h>
 #include <sys/device.h>
 #include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/sensors.h>
+#include <sys/sysctl.h>
 
 #include <machine/bus.h>
 #include <machine/fdt.h>
 
 #include <dev/ofw/openfirm.h>
 #include <dev/ofw/ofw_clock.h>
+#include <dev/ofw/ofw_misc.h>
 #include <dev/ofw/fdt.h>
 
 #include <dev/fdt/pscivar.h>
@@ -49,6 +54,7 @@ struct scmi_shmem {
 
 /* Protocols */
 #define SCMI_BASE		0x10
+#define SCMI_PERF		0x13
 #define SCMI_CLOCK		0x14
 
 /* Common messages */
@@ -64,6 +70,24 @@ struct scmi_shmem {
 #define SCMI_CLOCK_CONFIG_SET			0x7
 #define  SCMI_CLOCK_CONFIG_SET_ENABLE		(1 << 0)
 
+/* Performance management messages */
+#define SCMI_PERF_DOMAIN_ATTRIBUTES		0x3
+#define SCMI_PERF_DESCRIBE_LEVELS		0x4
+#define SCMI_PERF_LEVEL_GET			0x8
+
+struct scmi_resp_perf_describe_levels_40 {
+	uint16_t pl_nret;
+	uint16_t pl_nrem;
+	struct {
+		uint32_t	pe_perf;
+		uint32_t	pe_cost;
+		uint16_t	pe_latency;
+		uint16_t	pe_reserved;
+		uint32_t	pe_ifreq;
+		uint32_t	pe_lindex;
+	} pl_entry[];
+};
+
 static inline void
 scmi_message_header(volatile struct scmi_shmem *shmem,
     uint32_t protocol_id, uint32_t message_id)
@@ -71,20 +95,58 @@ scmi_message_header(volatile struct scmi_shmem *shmem,
 	shmem->message_header = (protocol_id << 10) | (message_id << 0);
 }
 
+struct scmi_perf_level {
+	uint32_t	pl_perf;
+	uint32_t	pl_cost;
+	uint32_t	pl_ifreq;
+};
 
+struct scmi_perf_domain {
+	size_t				pd_nlevels;
+	struct scmi_perf_level		*pd_levels;
+	int				pd_curlevel;
+};
+
 struct scmi_softc {
 	struct device			sc_dev;
 	bus_space_tag_t			sc_iot;
-	bus_space_handle_t		sc_ioh;
-	volatile struct scmi_shmem	*sc_shmem;
+	int				sc_node;
 
+	bus_space_handle_t		sc_ioh_tx;
+	bus_space_handle_t		sc_ioh_rx;
+	volatile struct scmi_shmem	*sc_shmem_tx;
+	volatile struct scmi_shmem	*sc_shmem_rx;
+
 	uint32_t			sc_smc_id;
+	struct mbox_channel		*sc_mc_tx;
+	struct mbox_channel		*sc_mc_rx;
 
+	uint16_t			sc_ver_major;
+	uint16_t			sc_ver_minor;
+
+	/* SCMI_CLOCK */
 	struct clock_device		sc_cd;
+
+	/* SCMI_PERF */
+	int				sc_perf_power_unit;
+#define SCMI_POWER_UNIT_UW	0x2
+#define SCMI_POWER_UNIT_MW	0x1
+#define SCMI_POWER_UNIT_NONE	0x0
+	size_t				sc_perf_ndomains;
+	struct scmi_perf_domain		*sc_perf_domains;
+
+	struct ksensordev		sc_perf_sensordev;
+	struct ksensordev		sc_perf_psensordev;
+	struct ksensor			*sc_perf_fsensors;
+	struct ksensor			*sc_perf_psensors;
+
+	int32_t				(*sc_command)(struct scmi_softc *);
 };
 
 int	scmi_match(struct device *, void *, void *);
 void	scmi_attach(struct device *, struct device *, void *);
+int	scmi_attach_smc(struct scmi_softc *, struct fdt_attach_args *);
+void	scmi_attach_mbox_deferred(struct device *);
 
 const struct cfattach scmi_ca = {
 	sizeof(struct scmi_softc), scmi_match, scmi_attach
@@ -96,22 +158,42 @@ struct cfdriver scmi_cd = {
 
 void	scmi_attach_proto(struct scmi_softc *, int);
 void	scmi_attach_clock(struct scmi_softc *, int);
-int32_t	scmi_command(struct scmi_softc *);
+void	scmi_attach_perf(struct scmi_softc *, int);
 
+int32_t	scmi_smc_command(struct scmi_softc *);
+int32_t	scmi_mbox_command(struct scmi_softc *);
+
 int
 scmi_match(struct device *parent, void *match, void *aux)
 {
 	struct fdt_attach_args *faa = aux;
 
-	return OF_is_compatible(faa->fa_node, "arm,scmi-smc");
+	return OF_is_compatible(faa->fa_node, "arm,scmi-smc") ||
+	    OF_is_compatible(faa->fa_node, "arm,scmi");
 }
 
 void
 scmi_attach(struct device *parent, struct device *self, void *aux)
 {
 	struct scmi_softc *sc = (struct scmi_softc *)self;
+	struct fdt_attach_args *faa = aux;
+
+	sc->sc_iot = faa->fa_iot;
+	sc->sc_node = faa->fa_node;
+
+	if (OF_is_compatible(faa->fa_node, "arm,scmi-smc")) {
+		scmi_attach_smc(sc, faa);
+	} else if (OF_is_compatible(faa->fa_node, "arm,scmi")) {
+		printf("\n");
+		/* Defer because we need the mailbox driver attached first */
+		config_defer(self, scmi_attach_mbox_deferred);
+	}
+}
+
+int
+scmi_attach_smc(struct scmi_softc *sc, struct fdt_attach_args *faa)
+{
 	volatile struct scmi_shmem *shmem;
-	struct fdt_attach_args *faa = aux;
 	struct fdt_reg reg;
 	int32_t status;
 	uint32_t version;
@@ -119,53 +201,142 @@ scmi_attach(struct device *parent, struct device *self
 	void *node;
 	int proto;
 
-	phandle = OF_getpropint(faa->fa_node, "shmem", 0);
-	node = fdt_find_phandle(phandle);
-	if (node == NULL || !fdt_is_compatible(node, "arm,scmi-shmem") ||
-	    fdt_get_reg(node, 0, &reg)) {
-		printf(": no shared memory\n");
-		return;
-	}
-
 	sc->sc_smc_id = OF_getpropint(faa->fa_node, "arm,smc-id", 0);
 	if (sc->sc_smc_id == 0) {
 		printf(": no SMC id\n");
-		return;
+		return -1;
 	}
 
-	sc->sc_iot = faa->fa_iot;
+	phandle = OF_getpropint(faa->fa_node, "shmem", 0);
+	node = fdt_find_phandle(phandle);
+	if (node == NULL || !fdt_is_compatible(node, "arm,scmi-shmem") ||
+	    fdt_get_reg(node, 0, &reg)) {
+		printf(": no shared memory\n");
+		return -1;
+	}
+
 	if (bus_space_map(sc->sc_iot, reg.addr,
-	    reg.size, 0, &sc->sc_ioh)) {
+	    reg.size, 0, &sc->sc_ioh_tx)) {
 		printf(": can't map shared memory\n");
-		return;
+		return -1;
 	}
-	sc->sc_shmem = bus_space_vaddr(sc->sc_iot, sc->sc_ioh);
-	shmem = sc->sc_shmem;
+	sc->sc_shmem_tx = bus_space_vaddr(sc->sc_iot, sc->sc_ioh_tx);
+	shmem = sc->sc_shmem_tx;
 
+	sc->sc_command = scmi_smc_command;
+
 	if ((shmem->channel_status & SCMI_CHANNEL_FREE) == 0) {
 		printf(": channel busy\n");
-		return;
+		return -1;
 	}
 
 	scmi_message_header(shmem, SCMI_BASE, SCMI_PROTOCOL_VERSION);
 	shmem->length = sizeof(uint32_t);
-	status = scmi_command(sc);
+	status = sc->sc_command(sc);
 	if (status != SCMI_SUCCESS) {
 		printf(": protocol version command failed\n");
-		return;
+		return -1;
 	}
 
 	version = shmem->message_payload[1];
-	printf(": SCMI %d.%d\n", version >> 16, version & 0xffff);
+	sc->sc_ver_major = version >> 16;
+	sc->sc_ver_minor = version & 0xfffff;
+	printf(": SCMI %d.%d\n", sc->sc_ver_major, sc->sc_ver_minor);
 
 	for (proto = OF_child(faa->fa_node); proto; proto = OF_peer(proto))
 		scmi_attach_proto(sc, proto);
+
+	return 0;
 }
 
+void
+scmi_attach_mbox_deferred(struct device *self)
+{
+	struct scmi_softc *sc = (struct scmi_softc *)self;
+	uint32_t *shmems;
+	int32_t status;
+	uint32_t version;
+	struct fdt_reg reg;
+	int len;
+	void *node;
+	int proto;
+
+	/* we only support the 2 mbox / 2 shmem case */
+	len = OF_getproplen(sc->sc_node, "mboxes");
+	if (len != 4 * sizeof(uint32_t)) {
+		printf("%s: invalid number of mboxes\n", sc->sc_dev.dv_xname);
+		return;
+	}
+
+	len = OF_getproplen(sc->sc_node, "shmem");
+	if (len != 2 * sizeof(uint32_t)) {
+		printf("%s: invalid number of shmems\n", sc->sc_dev.dv_xname);
+		return;
+	}
+
+	shmems = malloc(len, M_DEVBUF, M_WAITOK);
+	OF_getpropintarray(sc->sc_node, "shmem", shmems, len);
+
+	sc->sc_mc_tx = mbox_channel(sc->sc_node, "tx", NULL);
+	if (sc->sc_mc_tx == NULL) {
+		printf("%s: no tx mbox\n", sc->sc_dev.dv_xname);
+		return;
+	}
+	sc->sc_mc_rx = mbox_channel(sc->sc_node, "rx", NULL);
+	if (sc->sc_mc_rx == NULL) {
+		printf("%s: no rx mbox\n", sc->sc_dev.dv_xname);
+		return;
+	}
+
+	node = fdt_find_phandle(shmems[0]);
+	if (node == NULL || !fdt_is_compatible(node, "arm,scmi-shmem") ||
+	    fdt_get_reg(node, 0, &reg)) {
+		printf("%s: no shared memory\n", sc->sc_dev.dv_xname);
+		return;
+	}
+	if (bus_space_map(sc->sc_iot, reg.addr, reg.size, 0, &sc->sc_ioh_tx)) {
+		printf("%s: can't map shared memory\n", sc->sc_dev.dv_xname);
+		return;
+	}
+	sc->sc_shmem_tx = bus_space_vaddr(sc->sc_iot, sc->sc_ioh_tx);
+
+	node = fdt_find_phandle(shmems[1]);
+	if (node == NULL || !fdt_is_compatible(node, "arm,scmi-shmem") ||
+	    fdt_get_reg(node, 0, &reg)) {
+		printf("%s: no shared memory\n", sc->sc_dev.dv_xname);
+		return;
+	}
+	if (bus_space_map(sc->sc_iot, reg.addr, reg.size, 0, &sc->sc_ioh_rx)) {
+		printf("%s: can't map shared memory\n", sc->sc_dev.dv_xname);
+		return;
+	}
+	sc->sc_shmem_rx = bus_space_vaddr(sc->sc_iot, sc->sc_ioh_rx);
+
+	sc->sc_command = scmi_mbox_command;
+
+	scmi_message_header(sc->sc_shmem_tx, SCMI_BASE, SCMI_PROTOCOL_VERSION);
+	sc->sc_shmem_tx->length = sizeof(uint32_t);
+	status = sc->sc_command(sc);
+	if (status != SCMI_SUCCESS) {
+		printf("%s: protocol version command failed\n",
+		    sc->sc_dev.dv_xname);
+		return;
+	}
+
+	version = sc->sc_shmem_tx->message_payload[1];
+	sc->sc_ver_major = version >> 16;
+	sc->sc_ver_minor = version & 0xfffff;
+	printf("%s: SCMI %d.%d\n", sc->sc_dev.dv_xname, sc->sc_ver_major,
+	    sc->sc_ver_minor);
+
+	for (proto = OF_child(sc->sc_node); proto; proto = OF_peer(proto))
+		scmi_attach_proto(sc, proto);
+}
+
 int32_t
-scmi_command(struct scmi_softc *sc)
+scmi_smc_command(struct scmi_softc *sc)
 {
-	volatile struct scmi_shmem *shmem = sc->sc_shmem;
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
 	int32_t status;
 
 	shmem->channel_status = 0;
@@ -179,6 +350,32 @@ scmi_command(struct scmi_softc *sc)
 	return shmem->message_payload[0];
 }
 
+int32_t
+scmi_mbox_command(struct scmi_softc *sc)
+{
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
+	int ret;
+	int i;
+
+	shmem->channel_status = 0;
+	ret = mbox_send(sc->sc_mc_tx, NULL, 0);
+	if (ret != 0)
+		return SCMI_NOT_SUPPORTED; 
+
+	/* XXX: poll for now */
+	for (i = 0; i < 20; i++) {
+		if (shmem->channel_status & SCMI_CHANNEL_FREE)
+			break;
+		delay(10);
+	}
+	if ((shmem->channel_status & SCMI_CHANNEL_ERROR))
+		return SCMI_COMMS_ERROR;
+	if ((shmem->channel_status & SCMI_CHANNEL_FREE) == 0)
+		return SCMI_BUSY;
+
+	return shmem->message_payload[0];
+}
+
 void
 scmi_attach_proto(struct scmi_softc *sc, int node)
 {
@@ -186,6 +383,9 @@ scmi_attach_proto(struct scmi_softc *sc, int node)
 	case SCMI_CLOCK:
 		scmi_attach_clock(sc, node);
 		break;
+	case SCMI_PERF:
+		scmi_attach_perf(sc, node);
+		break;
 	default:
 		break;
 	}
@@ -200,13 +400,13 @@ int	scmi_clock_set_frequency(void *, uint32_t *, uint3
 void
 scmi_attach_clock(struct scmi_softc *sc, int node)
 {
-	volatile struct scmi_shmem *shmem = sc->sc_shmem;
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
 	int32_t status;
 	int nclocks;
 
 	scmi_message_header(shmem, SCMI_CLOCK, SCMI_PROTOCOL_ATTRIBUTES);
 	shmem->length = sizeof(uint32_t);
-	status = scmi_command(sc);
+	status = sc->sc_command(sc);
 	if (status != SCMI_SUCCESS)
 		return;
 
@@ -226,28 +426,28 @@ void
 scmi_clock_enable(void *cookie, uint32_t *cells, int on)
 {
 	struct scmi_softc *sc = cookie;
-	volatile struct scmi_shmem *shmem = sc->sc_shmem;
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
 	uint32_t idx = cells[0];
 
 	scmi_message_header(shmem, SCMI_CLOCK, SCMI_CLOCK_CONFIG_SET);
 	shmem->length = 3 * sizeof(uint32_t);
 	shmem->message_payload[0] = idx;
 	shmem->message_payload[1] = on ? SCMI_CLOCK_CONFIG_SET_ENABLE : 0;
-	scmi_command(sc);
+	sc->sc_command(sc);
 }
 
 uint32_t
 scmi_clock_get_frequency(void *cookie, uint32_t *cells)
 {
 	struct scmi_softc *sc = cookie;
-	volatile struct scmi_shmem *shmem = sc->sc_shmem;
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
 	uint32_t idx = cells[0];
 	int32_t status;
 
 	scmi_message_header(shmem, SCMI_CLOCK, SCMI_CLOCK_RATE_GET);
 	shmem->length = 2 * sizeof(uint32_t);
 	shmem->message_payload[0] = idx;
-	status = scmi_command(sc);
+	status = sc->sc_command(sc);
 	if (status != SCMI_SUCCESS)
 		return 0;
 	if (shmem->message_payload[2] != 0)
@@ -260,7 +460,7 @@ int
 scmi_clock_set_frequency(void *cookie, uint32_t *cells, uint32_t freq)
 {
 	struct scmi_softc *sc = cookie;
-	volatile struct scmi_shmem *shmem = sc->sc_shmem;
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
 	uint32_t idx = cells[0];
 	int32_t status;
 
@@ -270,9 +470,188 @@ scmi_clock_set_frequency(void *cookie, uint32_t *cells
 	shmem->message_payload[1] = idx;
 	shmem->message_payload[2] = freq;
 	shmem->message_payload[3] = 0;
-	status = scmi_command(sc);
+	status = sc->sc_command(sc);
 	if (status != SCMI_SUCCESS)
 		return -1;
 
 	return 0;
 }
+
+/* Performance management */
+void	scmi_perf_descr_levels(struct scmi_softc *, int);
+void	scmi_perf_refresh_sensor(void *);
+
+void
+scmi_attach_perf(struct scmi_softc *sc, int node)
+{
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
+	int32_t status;
+	uint32_t version;
+	int i;
+
+	scmi_message_header(sc->sc_shmem_tx, SCMI_PERF, SCMI_PROTOCOL_VERSION);
+	sc->sc_shmem_tx->length = sizeof(uint32_t);
+	status = sc->sc_command(sc);
+	if (status != SCMI_SUCCESS) {
+		printf("%s: SCMI_PROTOCOL_VERSION failed\n",
+		    sc->sc_dev.dv_xname);	
+		return;
+	}
+
+	version = shmem->message_payload[1];
+	if (version != 0x40000) {
+		printf("%s: invalid perf protocol version (0x%x != 0x4000)",
+		    sc->sc_dev.dv_xname, version);	
+		return;
+	}
+
+	scmi_message_header(shmem, SCMI_PERF, SCMI_PROTOCOL_ATTRIBUTES);
+	shmem->length = sizeof(uint32_t);
+	status = sc->sc_command(sc);
+	if (status != SCMI_SUCCESS) {
+		printf("%s: SCMI_PROTOCOL_ATTRIBUTES failed\n",
+		    sc->sc_dev.dv_xname);	
+		return;
+	}
+
+	sc->sc_perf_ndomains = shmem->message_payload[1] & 0xffff;
+	sc->sc_perf_domains = malloc(sc->sc_perf_ndomains *
+	    sizeof(struct scmi_perf_domain), M_DEVBUF, M_ZERO | M_WAITOK);
+	sc->sc_perf_power_unit = (shmem->message_payload[1] >> 16) & 0x3;
+
+	strlcpy(sc->sc_perf_sensordev.xname, sc->sc_dev.dv_xname,
+	    sizeof(sc->sc_perf_sensordev.xname));
+	
+	sc->sc_perf_fsensors =
+	    malloc(sc->sc_perf_ndomains * sizeof(struct ksensor),
+	    M_DEVBUF, M_ZERO | M_WAITOK);
+	sc->sc_perf_psensors =
+	    malloc(sc->sc_perf_ndomains * sizeof(struct ksensor),
+	    M_DEVBUF, M_ZERO | M_WAITOK);
+
+	/* Add one frequency sensor per perf domain */
+	for (i = 0; i < sc->sc_perf_ndomains; i++) {
+		scmi_message_header(shmem, SCMI_PERF,
+		    SCMI_PERF_DOMAIN_ATTRIBUTES);
+		shmem->length = 2 * sizeof(uint32_t);
+		shmem->message_payload[0] = i;
+		status = sc->sc_command(sc);
+		if (status != SCMI_SUCCESS) {
+			printf("%s: SCMI_PERF_DOMAIN_ATTRIBUTES failed\n",
+			    sc->sc_dev.dv_xname);	
+			goto err;
+		}
+
+		scmi_perf_descr_levels(sc, i);
+
+		sc->sc_perf_fsensors[i].type = SENSOR_FREQ;
+		sensor_attach(&sc->sc_perf_sensordev, &sc->sc_perf_fsensors[i]);
+		sc->sc_perf_psensors[i].type = SENSOR_WATTS;
+		sensor_attach(&sc->sc_perf_sensordev, &sc->sc_perf_psensors[i]);
+	}
+	sensordev_install(&sc->sc_perf_sensordev);
+	sensor_task_register(sc, scmi_perf_refresh_sensor, 1);
+	return;
+err:
+	free(sc->sc_perf_fsensors, M_DEVBUF,
+	    sc->sc_perf_ndomains * sizeof(struct ksensor));
+	free(sc->sc_perf_psensors, M_DEVBUF,
+	    sc->sc_perf_ndomains * sizeof(struct ksensor));
+}
+
+void
+scmi_perf_descr_levels(struct scmi_softc *sc, int domain)
+{
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
+	volatile struct scmi_resp_perf_describe_levels_40 *pl;
+	struct scmi_perf_domain *pd = &sc->sc_perf_domains[domain];
+	int status, i, idx;
+
+	idx = 0;
+	do {
+		scmi_message_header(shmem, SCMI_PERF,
+		    SCMI_PERF_DESCRIBE_LEVELS);
+		shmem->length = sizeof(uint32_t) * 3;
+		shmem->message_payload[0] = domain;
+		shmem->message_payload[1] = idx;
+		status = sc->sc_command(sc);
+		if (status != SCMI_SUCCESS) {
+			printf("%s: SCMI_PERF_DESCRIBE_LEVELS failed\n",
+			    sc->sc_dev.dv_xname);	
+			return;
+		}
+
+		pl = (struct scmi_resp_perf_describe_levels_40 *)
+		    &shmem->message_payload[1];
+
+		if (pd->pd_levels == NULL) {
+			pd->pd_nlevels = pl->pl_nret + pl->pl_nrem;
+			pd->pd_levels = malloc(pd->pd_nlevels *
+			    sizeof(struct scmi_perf_level),
+			    M_DEVBUF, M_ZERO | M_WAITOK);
+		}
+
+		for (i = 0; i < pl->pl_nret; i++) {
+			pd->pd_levels[idx + i].pl_cost =
+			    pl->pl_entry[i].pe_cost;
+			pd->pd_levels[idx + i].pl_perf =
+			    pl->pl_entry[i].pe_perf;
+			pd->pd_levels[idx + i].pl_ifreq =
+			    pl->pl_entry[i].pe_ifreq;
+		}
+		idx += pl->pl_nret;
+	} while (pl->pl_nrem);
+}
+
+void
+scmi_perf_refresh_sensor(void *arg)
+{
+	struct scmi_softc *sc = arg;
+	volatile struct scmi_shmem *shmem = sc->sc_shmem_tx;
+	uint64_t power_cost;
+	int32_t status;
+	int level, i;
+
+	if (sc->sc_perf_domains == NULL)
+		return;
+
+	for (i = 0; i < sc->sc_perf_ndomains; i++) {
+		if (sc->sc_perf_domains[i].pd_levels == NULL)
+			return;
+
+		scmi_message_header(shmem, SCMI_PERF,
+		    SCMI_PERF_LEVEL_GET);
+		shmem->length = sizeof(uint32_t) * 2;
+		shmem->message_payload[0] = i;
+		status = sc->sc_command(sc);
+		if (status != SCMI_SUCCESS) {
+			printf("%s: SCMI_PERF_LEVEL_GET failed\n",
+			    sc->sc_dev.dv_xname);	
+			return;
+		}
+
+		level = shmem->message_payload[1];
+		if (sc->sc_perf_fsensors == NULL ||
+		    sc->sc_perf_psensors == NULL)
+			return;
+
+		sc->sc_perf_domains[i].pd_curlevel = level;
+		sc->sc_perf_fsensors[i].value =
+		    (uint64_t)sc->sc_perf_domains[i].
+		    pd_levels[level].pl_ifreq * 1000000000;
+
+		switch (sc->sc_perf_power_unit) {
+		case SCMI_POWER_UNIT_UW:
+			power_cost = (uint64_t)sc->sc_perf_domains[i].
+			    pd_levels[level].pl_cost;
+			break;
+		case SCMI_POWER_UNIT_MW:
+			power_cost = (uint64_t)sc->sc_perf_domains[i].
+			    pd_levels[level].pl_cost * 1000;
+			break;
+		default:
+			continue;
+		}
+		sc->sc_perf_psensors[i].value = power_cost;
+	}
+}