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* Merge tag 'mailbox-v4.15' of ↵Linus Torvalds2017-11-151-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.linaro.org/landing-teams/working/fujitsu/integration Pull mailbox updates from Jassi Brar: "Change to POLL api and fixes for FlexRM and OMAP driver. Summary: - Core: Prefer ACK method over POLL, if both supported - Test: use flag instead of special character - FlexRM: Usual driver internal minor churn - Omap: fix error path" * tag 'mailbox-v4.15' of git://git.linaro.org/landing-teams/working/fujitsu/integration: mailbox/omap: unregister mbox class mailbox: mailbox-test: don't rely on rx_buffer content to signal data ready mailbox: reset txdone_method TXDONE_BY_POLL if client knows_txdone mailbox: Build Broadcom FlexRM driver as loadable module for iProc SOCs mailbox: bcm-flexrm-mailbox: Use common GPL comment header mailbox: bcm-flexrm-mailbox: add depends on ARCH_BCM_IPROC mailbox: bcm-flexrm-mailbox: Print ring number in errors and warnings mailbox: bcm-flexrm-mailbox: Fix FlexRM ring flush sequence
| * mailbox: reset txdone_method TXDONE_BY_POLL if client knows_txdoneSudeep Holla2017-11-141-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently the mailbox framework sets txdone_method to TXDONE_BY_POLL if the controller sets txdone_by_poll. However some clients can have a mechanism to do TXDONE_BY_ACK which they can specify by knows_txdone. However, we endup setting both TXDONE_BY_POLL and TXDONE_BY_ACK in that case. In such scenario, we may end up with below warnings as the tx ticker is run both by mailbox framework and the client. WARNING: CPU: 1 PID: 0 at kernel/time/hrtimer.c:805 hrtimer_forward+0x88/0xd8 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.12.0-rc5 #242 Hardware name: ARM LTD ARM Juno Development Platform task: ffff8009768ca700 task.stack: ffff8009768f8000 PC is at hrtimer_forward+0x88/0xd8 LR is at txdone_hrtimer+0xd4/0xf8 Call trace: hrtimer_forward+0x88/0xd8 __hrtimer_run_queues+0xe4/0x158 hrtimer_interrupt+0xa4/0x220 arch_timer_handler_phys+0x30/0x40 handle_percpu_devid_irq+0x78/0x130 generic_handle_irq+0x24/0x38 __handle_domain_irq+0x5c/0xb8 gic_handle_irq+0x54/0xa8 This patch fixes the issue by resetting TXDONE_BY_POLL if client has set knows_txdone. Cc: Alexey Klimov <alexey.klimov@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
* | mailbox: PCC: Move the MAX_PCC_SUBSPACES definition to header fileGeorge Cherian2017-11-091-1/+0
|/ | | | | | | | | Move the MAX_PCC_SUBSPACES definition to acpi/pcc.h file in preparation to add subspace ID support for cppc_acpi driver. Signed-off-by: George Cherian <george.cherian@cavium.com> Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* mailbox: pcc: Drop uninformative output during bootPunit Agrawal2017-08-101-3/+1
| | | | | | | | | | | | | | | | | When booting on an ACPI enabled system that does not provide the Platform Communications Channel Table (PCCT), the pcc mailbox driver prints - [ 0.484261] PCCT header not found. during probe before returning -ENODEV. This message clutters the bootlog and doesn't provide any useful information. Drop this message. Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Alexey Klimov <alexey.klimov@arm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* mailbox: pcc: Fix crash when request PCC channel 0Hoan Tran2017-07-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When PCCT is not available, kernel crashes as below when requests PCC channel 0. This patch fixes this issue. [ 0.920454] PCCT header not found. ... [ 8.031309] Unable to handle kernel NULL pointer dereference at virtual address 00000010 [ 8.031310] [0000000000000010] user address but active_mm is swapper [ 8.031312] Internal error: Oops: 96000004 [#1] PREEMPT SMP [ 8.031313] Modules linked in: [ 8.031316] CPU: 31 PID: 1 Comm: swapper/0 Tainted: G W 4.13.0-rc1 #18 [ 8.031317] Hardware name: AppliedMicro(R) 07/20/2017 [ 8.031318] task: ffff809ef3b08000 task.stack: ffff809ef3b10000 [ 8.031322] PC is at pcc_mbox_request_channel+0x8c/0x160 [ 8.031325] LR is at xgene_slimpro_i2c_probe+0x1c0/0x378 [ 8.031326] pc : [<ffff000008899450>] lr : [<ffff000008819dac>] pstate: 00000045 [ 8.031327] sp : ffff809ef3b13bd0 [ 8.031327] x29: ffff809ef3b13bd0 x28: ffff000008ed90a0 [ 8.031329] x27: ffff000009091000 x26: ffff000008e50470 [ 8.031330] x25: ffff000008ed9100 x24: ffff809eefd9ac30 [ 8.031332] x23: 0000000000000000 x22: ffff0000090e3e10 [ 8.031333] x21: ffff0000090e3000 x20: 0000000000000000 [ 8.031335] x19: 0000000000000000 x18: 0000000000087ffc [ 8.031336] x17: 2fe48d76a78303f0 x16: 0000000000087ffc [ 8.031337] x15: ffff000000000000 x14: 0000000000000000 [ 8.031339] x13: 0000000000000000 x12: 0000000000000018 [ 8.031340] x11: 0000000000000018 x10: 0101010101010101 [ 8.031342] x9 : 0000000000000000 x8 : 7f7f7f7f7f7f7f7f [ 8.031343] x7 : fefefefeff6b646d x6 : 0000008080808080 [ 8.031345] x5 : 0000000000000000 x4 : 0000000000000001 [ 8.031346] x3 : 0000000000000000 x2 : ffff000008819b64 [ 8.031348] x1 : 0000000000000000 x0 : 0000000000000000 ... [ 8.031393] Call trace: [ 8.031394] Exception stack(0xffff809ef3b13a00 to 0xffff809ef3b13b30) [ 8.031395] 3a00: 0000000000000000 0001000000000000 ffff809ef3b13bd0 ffff000008899450 [ 8.031397] 3a20: ffff809f7e1f9a10 ffff000008f60be0 0000000000000001 ffff809ef3b13b7c [ 8.031398] 3a40: ffff809f7e1f9a10 0000000000000000 ffff000009091000 0000000000000003 [ 8.031399] 3a60: ffff000009091000 0000000000000003 ffff809ef3b13a80 ffff0000084e0794 [ 8.031400] 3a80: ffff809ef3b13a90 ffff00000850bb64 ffff809ef3b13ad0 ffff00000850bf34 [ 8.031402] 3aa0: 0000000000000000 0000000000000000 ffff000008819b64 0000000000000000 [ 8.031403] 3ac0: 0000000000000001 0000000000000000 0000008080808080 fefefefeff6b646d [ 8.031404] 3ae0: 7f7f7f7f7f7f7f7f 0000000000000000 0101010101010101 0000000000000018 [ 8.031405] 3b00: 0000000000000018 0000000000000000 0000000000000000 ffff000000000000 [ 8.031406] 3b20: 0000000000087ffc 2fe48d76a78303f0 [ 8.031409] [<ffff000008899450>] pcc_mbox_request_channel+0x8c/0x160 [ 8.031410] [<ffff000008819dac>] xgene_slimpro_i2c_probe+0x1c0/0x378 [ 8.031413] [<ffff0000085e84dc>] platform_drv_probe+0x50/0xbc [ 8.031414] [<ffff0000085e68a4>] driver_probe_device+0x21c/0x2d0 [ 8.031416] [<ffff0000085e6a04>] __driver_attach+0xac/0xb0 [ 8.031417] [<ffff0000085e4a78>] bus_for_each_dev+0x58/0x98 [ 8.031418] [<ffff0000085e61e4>] driver_attach+0x20/0x28 [ 8.031419] [<ffff0000085e5e0c>] bus_add_driver+0x1c8/0x22c [ 8.031421] [<ffff0000085e7324>] driver_register+0x60/0xf4 [ 8.031422] [<ffff0000085e8420>] __platform_driver_register+0x4c/0x54 [ 8.031425] [<ffff000008e96dd0>] xgene_slimpro_i2c_driver_init+0x18/0x20 [ 8.031426] [<ffff000008083144>] do_one_initcall+0x38/0x124 [ 8.031429] [<ffff000008e50d0c>] kernel_init_freeable+0x190/0x22c [ 8.031431] [<ffff0000089eac30>] kernel_init+0x10/0xfc [ 8.031432] [<ffff000008082ec0>] ret_from_fork+0x10/0x50 [ 8.031434] Code: cb030e63 8b030013 b140067f 54fffda8 (f9400a61) [ 8.031448] ---[ end trace 14eb48a4e1e1f9fb ]--- Signed-off-by: Hoan Tran <hotran@apm.com> Acked-by: Prashanth Prakash <pprakash@codeaurora.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* ACPICA: Add support for new PCCT subtablesDavid E. Box2017-06-121-5/+5
| | | | | | | | | | | | ACPICA commit e7b817e3c405a4fb9ae9ee7ae4992b8c1f20d284 Extended PCC Subspaces (types 3 and 4) Link: https://github.com/acpica/acpica/commit/e7b817e3 Signed-off-by: David E. Box <david.e.box@linux.intel.com> Signed-off-by: Bob Moore <robert.moore@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* Merge branches 'acpica' and 'acpi-scan'Rafael J. Wysocki2016-12-221-4/+1
|\ | | | | | | | | | | | | | | | | | | | | * acpica: ACPI / osl: Remove deprecated acpi_get_table_with_size()/early_acpi_os_unmap_memory() ACPI / osl: Remove acpi_get_table_with_size()/early_acpi_os_unmap_memory() users ACPICA: Tables: Allow FADT to be customized with virtual address ACPICA: Tables: Back port acpi_get_table_with_size() and early_acpi_os_unmap_memory() from Linux kernel * acpi-scan: ACPI: do not warn if _BQC does not exist
| * ACPI / osl: Remove acpi_get_table_with_size()/early_acpi_os_unmap_memory() usersLv Zheng2016-12-211-4/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch removes the users of the deprectated APIs: acpi_get_table_with_size() early_acpi_os_unmap_memory() The following APIs should be used instead of: acpi_get_table() acpi_put_table() The deprecated APIs are invented to be a replacement of acpi_get_table() during the early stage so that the early mapped pointer will not be stored in ACPICA core and thus the late stage acpi_get_table() won't return a wrong pointer. The mapping size is returned just because it is required by early_acpi_os_unmap_memory() to unmap the pointer during early stage. But as the mapping size equals to the acpi_table_header.length (see acpi_tb_init_table_descriptor() and acpi_tb_validate_table()), when such a convenient result is returned, driver code will start to use it instead of accessing acpi_table_header to obtain the length. Thus this patch cleans up the drivers by replacing returned table size with acpi_table_header.length, and should be a no-op. Reported-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* | mailbox: PCC: Fix lockdep warning when request PCC channelHoan Tran2016-11-141-6/+7
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes the lockdep warning below DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) ------------[ cut here ]------------ WARNING: CPU: 1 PID: 1 at linux-next/kernel/locking/lockdep.c:2876 lockdep_trace_alloc+0xe0/0xf0 Modules linked in: CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.8.0-11756-g86c5152 #46 ... Call trace: Exception stack(0xffff8007da837890 to 0xffff8007da8379c0) 7880: ffff8007da834000 0001000000000000 78a0: ffff8007da837a70 ffff0000081111a0 00000000600000c5 000000000000003d 78c0: 9374bc6a7f3c7832 0000000000381878 ffff000009db7ab8 000000000000002f 78e0: ffff00000811aabc ffff000008be2548 ffff8007da837990 ffff00000811adf8 7900: ffff8007da834000 00000000024080c0 00000000000000c0 ffff000009021000 7920: 0000000000000000 0000000000000000 ffff000008c8f7c8 ffff8007da579810 7940: 000000000000002f ffff8007da858000 0000000000000000 0000000000000001 7960: 0000000000000001 0000000000000000 ffff00000811a468 0000000000000002 7980: 656c62617369645f 0000000000038187 00000000000000ee ffff8007da837850 79a0: ffff000009db50c0 ffff000009db569d 0000000000000006 ffff000089db568f [<ffff0000081111a0>] lockdep_trace_alloc+0xe0/0xf0 [<ffff0000081f4950>] __kmalloc_track_caller+0x50/0x250 [<ffff00000857c088>] devres_alloc_node+0x28/0x60 [<ffff0000081220e0>] devm_request_threaded_irq+0x50/0xe0 [<ffff0000087e6220>] pcc_mbox_request_channel+0x110/0x170 [<ffff0000084b2660>] acpi_cppc_processor_probe+0x264/0x414 [<ffff0000084ae9f4>] __acpi_processor_start+0x28/0xa0 [<ffff0000084aeab0>] acpi_processor_start+0x44/0x54 [<ffff00000857897c>] driver_probe_device+0x1fc/0x2b0 [<ffff000008578ae4>] __driver_attach+0xb4/0xc0 [<ffff00000857683c>] bus_for_each_dev+0x5c/0xa0 [<ffff000008578110>] driver_attach+0x20/0x30 [<ffff000008577c20>] bus_add_driver+0x110/0x230 [<ffff000008579320>] driver_register+0x60/0x100 [<ffff000008d478b8>] acpi_processor_driver_init+0x2c/0xb0 [<ffff000008083168>] do_one_initcall+0x38/0x130 [<ffff000008d20d6c>] kernel_init_freeable+0x210/0x2b4 [<ffff000008945d90>] kernel_init+0x10/0x110 [<ffff000008082e80>] ret_from_fork+0x10/0x50 It's because the spinlock inside pcc_mbox_request_channel() is kept too long. This patch releases spinlock before request_irq() and free_irq() to fix this issue as spinlock is only needed to protect the channel data. Signed-off-by: Hoan Tran <hotran@apm.com> Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* mailbox: pcc: Support HW-Reduced Communication Subspace type 2hotran2016-08-311-71/+245
| | | | | | | | | | | ACPI 6.1 has a PCC HW-Reduced Communication Subspace type 2 intended for use on HW-Reduce ACPI Platform, which requires read-modify-write sequence to acknowledge doorbell interrupt. This patch provides the implementation for the Communication Subspace Type 2. Signed-off-by: Hoan Tran <hotran@apm.com> Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
*-. Merge branches 'pm-cpufreq', 'pm-cpuidle' and 'acpi-cppc'Rafael J. Wysocki2016-04-081-2/+2
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * pm-cpufreq: cpufreq: dt: Drop stale comment cpufreq: intel_pstate: Documenation for structures cpufreq: intel_pstate: fix inconsistency in setting policy limits intel_pstate: Avoid extra invocation of intel_pstate_sample() intel_pstate: Do not set utilization update hook too early * pm-cpuidle: intel_idle: Add KBL support intel_idle: Add SKX support intel_idle: Clean up all registered devices on exit. intel_idle: Propagate hot plug errors. intel_idle: Don't overreact to a cpuidle registration failure. intel_idle: Setup the timer broadcast only on successful driver load. intel_idle: Avoid a double free of the per-CPU data. intel_idle: Fix dangling registration on error path. intel_idle: Fix deallocation order on the driver exit path. intel_idle: Remove redundant initialization calls. intel_idle: Fix a helper function's return value. intel_idle: remove useless return from void function. * acpi-cppc: mailbox: pcc: Don't access an unmapped memory address space
| | * mailbox: pcc: Don't access an unmapped memory address spaceShanker Donthineni2016-04-071-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The acpi_pcc_probe() may end up accessing memory outside of the PCCT table space causing the kernel panic(). Increment the pcct_entry pointer after parsing 'HW-reduced Communications Subspace' to fix the problem. This change also enables the parsing of subtable at index 0. Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org> Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* | | Merge branches 'acpi-processor' and 'acpi-cppc'Rafael J. Wysocki2016-03-141-7/+104
|\ \ \ | |/ / |/| / | |/ | | | | | | | | | | | | | | | | | | | | * acpi-processor: ACPI / sleep: move acpi_processor_sleep to sleep.c ACPI / processor : add support for ACPI0010 processor container ACPI / processor_idle: replace PREFIX with pr_fmt * acpi-cppc: ACPI / CPPC: use MRTT/MPAR to decide if/when a req can be sent ACPI / CPPC: replace writeX/readX to PCC with relaxed version mailbox: pcc: optimized pcc_send_data ACPI / CPPC: optimized cpc_read and cpc_write ACPI / CPPC: Optimize PCC Read Write operations
| * mailbox: pcc: optimized pcc_send_dataPrakash, Prashanth2016-03-091-7/+104
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | pcc_send_data() can be invoked during the execution of performance critical code as in cppc_cpufreq driver. With acpi_* APIs, the doorbell register accessed in pcc_send_data() if present in system memory will be searched (in cached virt to phys addr mapping), mapped, read/written and then unmapped. These operations take significant amount of time. This patch maps the performance critical doorbell register during init and then reads/writes to it directly using the mapped virtual address. This patch + similar changes to CPPC acpi driver reduce the time per freq. transition from around 200us to about 20us for the CPPC cpufreq driver Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org> Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* | mailbox: pcc: fix channel calculation in get_pcc_channel()Alexey Klimov2016-02-021-7/+1
|/ | | | | | | | | | | | | | | | | | | | | | | This patch fixes the calculation of pcc_chan for non-zero id. After the compiler ignores the (unsigned long) cast the pcc_mbox_channels pointer is type-cast and then the type-cast offset is added which results in address outside of the range leading to the kernel crashing. We might add braces and make it: pcc_chan = (struct mbox_chan *) ((unsigned long) pcc_mbox_channels + (id * sizeof(*pcc_chan))); but let's go with array approach here and use id as index. Tested on Juno board. Signed-off-by: Alexey Klimov <alexey.klimov@arm.com> Acked-by: Sudeep Holla <sudeep.holla@arm.com> Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
* PCC: fix dereference of ERR_PTRSudip Mukherjee2015-10-161-1/+1
| | | | | | | get_pcc_channel() does not return NULL on error it returns the error code in ERR_PTR, but we have been checking it for NULL. Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
* PCC: Initialize PCC Mailbox earlier at bootAshwin Chaugule2015-08-251-1/+7
| | | | | | | | | | | | | This change initializes the PCC Mailbox earlier than the ACPI processor driver. This enables drivers introduced in follow up patches (e.g. CPPC) to be probed via the ACPI processor driver interface. The CPPC probe requires the PCC channel to be initialized for it to query each CPUs performance capabilities. Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Reviewed-by: Al Stone <al.stone@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* mailbox: Make mbox_chan_ops constAndrew Bresticker2015-05-121-1/+1
| | | | | | | | | | | The mailbox controller's channel ops ought to be read-only. Update all the mailbox drivers to make their mbox_chan_ops const as well. Signed-off-by: Andrew Bresticker <abrestic@chromium.org> Cc: Ashwin Chaugule <ashwin.chaugule@linaro.org> Cc: Ley Foon Tan <lftan@altera.com> Acked-by: Suman Anna <s-anna@ti.com> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
* Mailbox: Restructure and simplify PCC mailbox codeAshwin Chaugule2015-03-041-85/+37
| | | | | | | | | | | | | | Previously the PCC driver depended on the client side to map the communication space base address. This region was was then used in the PCC driver and the client side. The client side used this region to read and write its data and the PCC driver used it to only write the PCC command. Removing this split simplifies the PCC driver a lot. This patch moves all communication region read/writes to the client side. The PCC clients can now drive the PCC mailbox controller via the mbox_client_txdone() method. Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
* Merge branch 'mailbox-devel' of ↵Linus Torvalds2015-02-111-2/+2
|\ | | | | | | | | | | | | | | | | | | | | git://git.linaro.org/landing-teams/working/fujitsu/integration Pull mailbox framework updates from Jassi Brar. * 'mailbox-devel' of git://git.linaro.org/landing-teams/working/fujitsu/integration: mailbox: Add Altera mailbox driver mailbox: check for bit set before polling Mailbox: Fix return value check in pcc_init()
| * Mailbox: Fix return value check in pcc_init()Wei Yongjun2015-02-061-2/+2
| | | | | | | | | | | | | | | | In case of error, the function platform_create_bundle() returns ERR_PTR() and never returns NULL. The NULL test in the return value check should be replaced with IS_ERR(). Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
* | ACPI / PCC: Use pr_debug() for debug messages in pcc_init()Rafael J. Wysocki2015-02-051-2/+2
|/ | | | | | | | pcc_init() uses pr_err() to print two messages that are really debug and not interesting to users. Replace those pr_err() with pr_debug(). Reported-by: Cristian <caravena@gmail.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* Mailbox: Add support for Platform Communication ChannelAshwin Chaugule2014-11-271-0/+403
ACPI 5.0+ spec defines a generic mode of communication between the OS and a platform such as the BMC. This medium (PCC) is typically used by CPPC (ACPI CPU Performance management), RAS (ACPI reliability protocol) and MPST (ACPI Memory power states). This patch adds PCC support as a Mailbox Controller. As of ACPI v5.1 there is no provision for clients to lookup mailbox controllers in a way that Linux expects. e.g. in DT the clients can list the mailboxes they can associate with in the DT binding and then provide a unique index to lookup a channel within a mailbox. Since the ACPI spec doesn't have anything similar, we introduce a mailbox controller specific API so that when the client calls it, we know to lookup in the context of a specific controller. This also helps in keeping a consistent interface across DT and ACPI for such drivers. This patch implements basic PCC support using the ACPI v5.1 structures. IRQ mode support will be provided as follow up patches. Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Reviewed-by: Mark Brown <broonie@kernel.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>