From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751304AbbJBVGO (ORCPT ); Fri, 2 Oct 2015 17:06:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51895 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751299AbbJBVGL (ORCPT ); Fri, 2 Oct 2015 17:06:11 -0400 Subject: Re: [PATCH v3 1/7] acpi: Add early device probing infrastructure To: Marc Zyngier , "Rafael J. Wysocki" , Len Brown , Hanjun Guo , Tomasz Nowicki , Thomas Gleixner , Jason Cooper , Lorenzo Pieralisi , Sudeep Holla , Will Deacon , Catalin Marinas , Daniel Lezcano References: <1443451758-22717-1-git-send-email-marc.zyngier@arm.com> <1443451758-22717-2-git-send-email-marc.zyngier@arm.com> Cc: linaro-acpi@lists.linaro.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org From: Wei Huang Message-ID: <560EF1BD.1020004@redhat.com> Date: Fri, 2 Oct 2015 16:06:05 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <1443451758-22717-2-git-send-email-marc.zyngier@arm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, On 09/28/2015 09:49 AM, Marc Zyngier wrote: > IRQ controllers and timers are the two types of device the kernel > requires before being able to use the device driver model. > > ACPI so far lacks a proper probing infrastructure similar to the one > we have with DT, where we're able to declare IRQ chips and > clocksources inside the driver code, and let the core code pick it up > and call us back on a match. This leads to all kind of really ugly > hacks all over the arm64 code and even in the ACPI layer. > > In order to allow some basic probing based on the ACPI tables, > introduce "struct acpi_probe_entry" which contains just enough > data and callbacks to match a table, an optional subtable, and > call a probe function. A driver can, at build time, register itself > and expect being called if the right entry exists in the ACPI > table. > > A acpi_probe_device_table() is provided, taking an identifier for > a set of acpi_prove_entries, and iterating over the registered > entries. > > Signed-off-by: Marc Zyngier > --- > drivers/acpi/scan.c | 39 +++++++++++++++++++++++ > include/asm-generic/vmlinux.lds.h | 10 ++++++ > include/linux/acpi.h | 66 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 115 insertions(+) > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index f834b8c..daf9fc8 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -1913,3 +1913,42 @@ int __init acpi_scan_init(void) > mutex_unlock(&acpi_scan_lock); > return result; > } > + > +static struct acpi_probe_entry *ape; > +static int acpi_probe_count; > +static DEFINE_SPINLOCK(acpi_probe_lock); > + > +static int __init acpi_match_madt(struct acpi_subtable_header *header, > + const unsigned long end) > +{ > + if (!ape->subtable_valid || ape->subtable_valid(header, ape)) > + if (!ape->probe_subtbl(header, end)) > + acpi_probe_count++; > + > + return 0; > +} > + > +int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr) > +{ > + int count = 0; > + > + if (acpi_disabled) > + return 0; > + > + spin_lock(&acpi_probe_lock); > + for (ape = ap_head; nr; ape++, nr--) { > + if (ACPI_COMPARE_NAME(ACPI_SIG_MADT, ape->id)) { > + acpi_probe_count = 0; > + acpi_table_parse_madt(ape->type, acpi_match_madt, 0); > + count += acpi_probe_count; > + } else { > + int res; > + res = acpi_table_parse(ape->id, ape->probe_table); > + if (!res) > + count++; > + } > + } > + spin_unlock(&acpi_probe_lock); > + > + return count; > +} > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > index 1781e54..efd7ed1 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -181,6 +181,16 @@ > #define CPUIDLE_METHOD_OF_TABLES() OF_TABLE(CONFIG_CPU_IDLE, cpuidle_method) > #define EARLYCON_OF_TABLES() OF_TABLE(CONFIG_SERIAL_EARLYCON, earlycon) > > +#ifdef CONFIG_ACPI > +#define ACPI_PROBE_TABLE(name) \ > + . = ALIGN(8); \ > + VMLINUX_SYMBOL(__##name##_acpi_probe_table) = .; \ > + *(__##name##_acpi_probe_table) \ > + VMLINUX_SYMBOL(__##name##_acpi_probe_table_end) = .; > +#else > +#define ACPI_PROBE_TABLE(name) > +#endif > + > #define KERNEL_DTB() \ > STRUCT_ALIGN(); \ > VMLINUX_SYMBOL(__dtb_start) = .; \ > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 84e7055..51a96a8 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -787,6 +787,61 @@ int acpi_dev_prop_read(struct acpi_device *adev, const char *propname, > > struct fwnode_handle *acpi_get_next_subnode(struct device *dev, > struct fwnode_handle *subnode); > + > +struct acpi_probe_entry; > +typedef bool (*acpi_probe_entry_validate_subtbl)(struct acpi_subtable_header *, > + struct acpi_probe_entry *); > + > +#define ACPI_TABLE_ID_LEN 5 > + > +/** > + * struct acpi_probe_entry - boot-time probing entry > + * @id: ACPI table name > + * @type: Optional subtable type to match > + * (if @id contains subtables) > + * @subtable_valid: Optional callback to check the validity of > + * the subtable > + * @probe_table: Callback to the driver being probed when table > + * match is successful > + * @probe_subtbl: Callback to the driver being probed when table and > + * subtable match (and optional callback is successful) > + * @driver_data: Sideband data provided back to the driver > + */ A suggestion: could you add more details to the description above? I couldn't figure how to use it without reading __acpi_probe_device_table(). Something like "if @id matches the one defined in __acpi_probe_device_table(), then probe_subtbl() will be invoked; otherwise probe_table() will be invoked" would be helpful for programmers use this struct. > +struct acpi_probe_entry { > + __u8 id[ACPI_TABLE_ID_LEN]; > + __u8 type; > + acpi_probe_entry_validate_subtbl subtable_valid; > + union { > + acpi_tbl_table_handler probe_table; > + acpi_tbl_entry_handler probe_subtbl; > + }; Could we avoid using union for probe_table & probe_subtbl? The benefit is that we don't need to do function casting below and compiler can automatically check the correctness. > + kernel_ulong_t driver_data; > +}; > + > +#define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable, valid, data, fn) \ > + static const struct acpi_probe_entry __acpi_probe_##name \ > + __used __section(__##table##_acpi_probe_table) \ > + = { \ > + .id = table_id, \ > + .type = subtable, \ > + .subtable_valid = valid, \ > + .probe_table = (acpi_tbl_table_handler)fn, \ > + .driver_data = data, \ > + } > + Something like: #define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable, valid, data, fn, subfn) \ static const struct acpi_probe_entry __acpi_probe_##name \ __used __section(__##table##_acpi_probe_table) \ = { \ .id = table_id, \ .type = subtable, \ .subtable_valid = valid, \ .probe_table = fn, \ .probe_subtbl = subfn, \ .driver_data = data, \ } Then in patch 3, you can define new entries as: IRQCHIP_ACPI_DECLARE(gic_v2, ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR, gic_validate_dist, ACPI_MADT_GIC_VERSION_V2, NULL, gic_v2_acpi_init); IRQCHIP_ACPI_DECLARE(gic_v2_maybe, ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR, gic_validate_dist, ACPI_MADT_GIC_VERSION_NONE, NULL, gic_v2_acpi_init); > +#define ACPI_PROBE_TABLE(name) __##name##_acpi_probe_table > +#define ACPI_PROBE_TABLE_END(name) __##name##_acpi_probe_table_end > + > +int __acpi_probe_device_table(struct acpi_probe_entry *start, int nr); > + > +#define acpi_probe_device_table(t) \ > + ({ \ > + extern struct acpi_probe_entry ACPI_PROBE_TABLE(t), \ > + ACPI_PROBE_TABLE_END(t); \ > + __acpi_probe_device_table(&ACPI_PROBE_TABLE(t), \ > + (&ACPI_PROBE_TABLE_END(t) - \ > + &ACPI_PROBE_TABLE(t))); \ > + }) > #else > static inline int acpi_dev_get_property(struct acpi_device *adev, > const char *name, acpi_object_type type, > @@ -845,6 +900,17 @@ static inline struct fwnode_handle *acpi_get_next_subnode(struct device *dev, > { > return NULL; > } > + > +#define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable, validate, data, fn) \ > + static const void * __acpi_table_##name[] \ > + __attribute__((unused)) \ > + = { (void *) table_id, \ > + (void *) subtable, \ > + (void *) valid, \ > + (void *) fn, \ > + (void *) data } > + > +#define acpi_probe_device_table(t) ({ int __r = 0; __r;}) > #endif > > #endif /*_LINUX_ACPI_H*/ >