/* $NetBSD: acpi_pcc.c,v 1.1 2020/12/13 20:27:53 jmcneill Exp $ */
/*-
* Copyright (c) 2020 Jared McNeill <
[email protected]>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Platform Communications Channel (PCC) device driver.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: acpi_pcc.c,v 1.1 2020/12/13 20:27:53 jmcneill Exp $");
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/cpu.h>
#include <sys/device.h>
#include <sys/kmem.h>
#include <dev/acpi/acpireg.h>
#include <dev/acpi/acpivar.h>
#include <dev/acpi/acpi_pcc.h>
#define PCC_MEMORY_BARRIER() membar_sync()
#if defined(__aarch64__)
#define PCC_DMA_BARRIER() __asm __volatile("dsb sy" ::: "memory")
#else
#error PCC_BARRIER not implemented on this platform
#endif
#define PCC_SIGNATURE(space_id) (0x50434300 | (space_id))
#define PCC_STATUS_COMMAND_COMPLETE __BIT(0)
#define PCC_STATUS_COMMAND_ERROR __BIT(2)
struct pcc_register {
ACPI_GENERIC_ADDRESS reg_addr;
uint64_t reg_preserve;
uint64_t reg_set;
};
struct pcc_subspace {
uint8_t ss_id;
uint8_t ss_type;
void * ss_data;
size_t ss_len;
struct pcc_register ss_doorbell_reg;
uint32_t ss_latency;
uint32_t ss_turnaround;
kmutex_t ss_lock;
};
struct pcc_softc {
device_t sc_dev;
struct pcc_subspace * sc_ss;
u_int sc_nss;
};
typedef void (*pcc_subspace_callback)(ACPI_SUBTABLE_HEADER *, uint8_t, void *);
static int pcc_match(device_t, cfdata_t, void *);
static void pcc_attach(device_t, device_t, void *);
static uint8_t pcc_subspace_foreach(ACPI_TABLE_PCCT *,
pcc_subspace_callback, void *);
static void pcc_subspace_attach(ACPI_SUBTABLE_HEADER *, uint8_t, void *);
static struct pcc_softc *pcc_softc = NULL;
CFATTACH_DECL_NEW(acpipcc, sizeof(struct pcc_softc),
pcc_match, pcc_attach, NULL, NULL);
static int
pcc_match(device_t parent, cfdata_t cf, void *aux)
{
ACPI_TABLE_HEADER *hdrp = aux;
return memcmp(hdrp->Signature, ACPI_SIG_PCCT, ACPI_NAMESEG_SIZE) == 0;
}
static void
pcc_attach(device_t parent, device_t self, void *aux)
{
struct pcc_softc * const sc = device_private(self);
ACPI_TABLE_PCCT *pcct = aux;
u_int count;
if (pcc_softc != NULL) {
aprint_error(": Already attached!\n");
return;
}
count = pcc_subspace_foreach(pcct, NULL, NULL);
if (count == 0) {
aprint_error(": No subspaces found!\n");
return;
}
aprint_naive("\n");
aprint_normal(": Platform Communications Channel, %u subspace%s\n",
count, count == 1 ? "" : "s");
sc->sc_dev = self;
sc->sc_nss = count;
sc->sc_ss = kmem_zalloc(count * sizeof(*sc->sc_ss), KM_SLEEP);
pcc_subspace_foreach(pcct, pcc_subspace_attach, sc);
pcc_softc = sc;
}
/*
* pcc_subspace_foreach --
*
* Find all subspaces defined in the PCCT table. If a 'func' callback
* is provided, the callback is invoked for each subspace with the
* table pointer, subspace ID, and 'arg' as arguments. Returns the
* number of subspaces found.
*/
static uint8_t
pcc_subspace_foreach(ACPI_TABLE_PCCT *pcct, pcc_subspace_callback func,
void *arg)
{
ACPI_SUBTABLE_HEADER *header;
char *ptr, *end;
uint8_t count;
end = (char *)pcct + pcct->Header.Length;
ptr = (char *)pcct + sizeof(*pcct);
count = 0;
while (ptr < end && count < 255) {
header = (ACPI_SUBTABLE_HEADER *)ptr;
if (header->Length == 0 || ptr + header->Length > end) {
break;
}
if (func != NULL) {
func(header, count, arg);
}
++count;
ptr += header->Length;
}
return count;
}
/*
* pcc_subspace_attach --
*
* Allocate resources for a PCC subspace.
*/
static void
pcc_subspace_attach(ACPI_SUBTABLE_HEADER *header, uint8_t id, void *arg)
{
struct pcc_softc * const sc = arg;
struct pcc_subspace * const ss = &sc->sc_ss[id];
ACPI_PCCT_SUBSPACE *generic = (ACPI_PCCT_SUBSPACE *)header;
ss->ss_id = id;
ss->ss_type = header->Type;
ss->ss_data = AcpiOsMapMemory(generic->BaseAddress, generic->Length);
if (ss->ss_data == NULL) {
panic("%s: couldn't map subspace 0x%02x at 0x%016" PRIx64,
device_xname(sc->sc_dev), id, generic->BaseAddress);
}
ss->ss_len = generic->Length;
ss->ss_doorbell_reg.reg_addr = generic->DoorbellRegister;
ss->ss_doorbell_reg.reg_preserve = generic->PreserveMask;
ss->ss_doorbell_reg.reg_set = generic->WriteMask;
mutex_init(&ss->ss_lock, MUTEX_DEFAULT, IPL_NONE);
}
/*
* pcc_wait_command --
*
* Wait for command complete to be set on a PCC subspace, with timeout.
*/
static ACPI_STATUS
pcc_wait_command(struct pcc_subspace *ss, bool first)
{
volatile ACPI_PCCT_SHARED_MEMORY *shmem;
int retry;
switch (ss->ss_type) {
case ACPI_PCCT_TYPE_GENERIC_SUBSPACE:
/*
* OSPM does not have to wait for command complete before
* sending the first command.
*/
if (first) {
return AE_OK;
}
/* FALLTHROUGH */
case ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE:
case ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2:
/*
* Wait for the command complete bit to be set in the status
* register.
*/
shmem = ss->ss_data;
retry = imax(1000, ss->ss_turnaround + ss->ss_latency * 100);
while (retry > 0) {
PCC_MEMORY_BARRIER();
if ((shmem->Status & PCC_STATUS_COMMAND_COMPLETE) != 0)
return AE_OK;
delay(10);
retry -= 10;
}
return AE_TIME;
default:
return AE_NOT_IMPLEMENTED;
}
}
/*
* pcc_doorbell --
*
* Ring the door bell by writing to the doorbell register.
*/
static ACPI_STATUS
pcc_doorbell(struct pcc_register *reg)
{
ACPI_STATUS rv;
UINT64 val;
rv = AcpiRead(&val, ®->reg_addr);
if (ACPI_FAILURE(rv)) {
return rv;
}
val &= reg->reg_preserve;
val |= reg->reg_set;
return AcpiWrite(val, ®->reg_addr);
}
/*
* pcc_send_command --
*
* Write a command into PCC subspace and ring the doorbell.
*/
static ACPI_STATUS
pcc_send_command(struct pcc_subspace *ss, ACPI_GENERIC_ADDRESS *reg,
uint32_t command, int flags, ACPI_INTEGER val)
{
volatile ACPI_PCCT_SHARED_MEMORY *shmem = ss->ss_data;
uint8_t *data = __UNVOLATILE(shmem + 1);
UINT64 tmp, mask;
KASSERT(ss->ss_type == ACPI_PCCT_TYPE_GENERIC_SUBSPACE ||
ss->ss_type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
ss->ss_type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2);
shmem->Signature = PCC_SIGNATURE(ss->ss_id);
shmem->Command = command & 0xff;
if ((flags & PCC_WRITE) != 0) {
mask = __BITS(reg->BitOffset + reg->BitWidth - 1,
reg->BitOffset);
ACPI_MOVE_64_TO_64(&tmp, data + reg->Address);
tmp &= mask;
tmp |= __SHIFTIN(val, mask);
ACPI_MOVE_64_TO_64(data + reg->Address, &tmp);
}
PCC_MEMORY_BARRIER();
shmem->Status &= ~(PCC_STATUS_COMMAND_COMPLETE |
PCC_STATUS_COMMAND_ERROR);
PCC_DMA_BARRIER();
return pcc_doorbell(&ss->ss_doorbell_reg);
}
/*
* pcc_receive_response --
*
* Process a command response in PCC subspace.
*/
static ACPI_STATUS
pcc_receive_response(struct pcc_subspace *ss, ACPI_GENERIC_ADDRESS *reg,
int flags, ACPI_INTEGER *val)
{
volatile ACPI_PCCT_SHARED_MEMORY *shmem = ss->ss_data;
const uint8_t *data = __UNVOLATILE(shmem + 1);
UINT64 tmp, mask;
KASSERT(ss->ss_type == ACPI_PCCT_TYPE_GENERIC_SUBSPACE ||
ss->ss_type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
ss->ss_type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2);
KASSERT((shmem->Status & PCC_STATUS_COMMAND_COMPLETE) != 0);
if ((shmem->Status & PCC_STATUS_COMMAND_ERROR) != 0) {
return AE_ERROR;
}
if ((flags & PCC_READ) != 0) {
mask = __BITS(reg->BitOffset + reg->BitWidth - 1,
reg->BitOffset);
ACPI_MOVE_64_TO_64(&tmp, data + reg->Address);
*val = __SHIFTOUT(tmp, mask);
}
return AE_OK;
}
/*
* pcc_message --
*
* Send or receive a command over a PCC subspace.
*/
ACPI_STATUS
pcc_message(ACPI_GENERIC_ADDRESS *reg, uint32_t command, int flags,
ACPI_INTEGER *val)
{
struct pcc_softc * const sc = pcc_softc;
struct pcc_subspace *ss;
uint8_t ss_id;
ACPI_STATUS rv;
/* The "Access Width" in the PCC GAS is the Subspace ID */
ss_id = reg->AccessWidth;
if (sc == NULL) {
return AE_NOT_CONFIGURED;
}
if (ss_id >= sc->sc_nss) {
return AE_NOT_FOUND;
}
ss = &sc->sc_ss[ss_id];
switch (ss->ss_type) {
case ACPI_PCCT_TYPE_GENERIC_SUBSPACE:
case ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE:
case ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2:
break;
default:
return AE_NOT_IMPLEMENTED;
}
mutex_enter(&ss->ss_lock);
/* Wait for any previous commands to finish. */
rv = pcc_wait_command(ss, true);
if (ACPI_FAILURE(rv)) {
goto unlock;
}
/* Place command into subspace and ring the doorbell */
rv = pcc_send_command(ss, reg, command, flags, *val);
if (ACPI_FAILURE(rv)) {
goto unlock;
}
/* Wait for command to complete. */
rv = pcc_wait_command(ss, false);
if (ACPI_FAILURE(rv)) {
goto unlock;
}
/* Process the command response */
rv = pcc_receive_response(ss, reg, flags, val);
if (ss->ss_turnaround != 0)
delay(ss->ss_turnaround);
unlock:
mutex_exit(&ss->ss_lock);
return rv;
}
