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From: Marc Zyngier <maz@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: "Thomas Gleixner" <tglx@linutronix.de>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"Paul Mackerras" <paulus@samba.org>,
	"Ley Foon Tan" <ley.foon.tan@intel.com>,
	"Chris Zankel" <chris@zankel.net>,
	"Max Filippov" <jcmvbkbc@gmail.com>,
	"Vineet Gupta" <vgupta@synopsys.com>,
	"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
	"Robert Jarzmik" <robert.jarzmik@free.fr>,
	"Russell King" <linux@armlinux.org.uk>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
	"Yoshinori Sato" <ysato@users.sourceforge.jp>,
	"Rich Felker" <dalias@libc.org>,
	"Geert Uytterhoeven" <geert@linux-m68k.org>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Christian König" <christian.koenig@amd.com>,
	"David Airlie" <airlied@linux.ie>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Rob Clark" <robdclark@gmail.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Lee Jones" <lee.jones@linaro.org>,
	"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	"Rob Herring" <robh@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Bartosz Golaszewski" <bgolaszewski@baylibre.com>,
	kernel-team@android.com
Subject: [PATCH v2 14/14] Documentation: Update irq_domain.rst with new lookup APIs
Date: Mon,  2 Aug 2021 17:26:30 +0100	[thread overview]
Message-ID: <20210802162630.2219813-15-maz@kernel.org> (raw)
In-Reply-To: <20210802162630.2219813-1-maz@kernel.org>

Catch up with the recent irqdomain updates, and document
{generic_,}handle_domain_irq(), irq_resolve_mapping() as well
as the deprecation of some of the older APIs.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 Documentation/core-api/irq/irq-domain.rst | 28 ++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/Documentation/core-api/irq/irq-domain.rst b/Documentation/core-api/irq/irq-domain.rst
index 53283b3729a1..6979b4af2c1f 100644
--- a/Documentation/core-api/irq/irq-domain.rst
+++ b/Documentation/core-api/irq/irq-domain.rst
@@ -55,8 +55,24 @@ exist then it will allocate a new Linux irq_desc, associate it with
 the hwirq, and call the .map() callback so the driver can perform any
 required hardware setup.
 
-When an interrupt is received, irq_find_mapping() function should
-be used to find the Linux IRQ number from the hwirq number.
+Once a mapping has been established, it can be retrieved or used via a
+variety of methods:
+
+- irq_resolve_mapping() returns a pointer to the irq_desc structure
+  for a given domain and hwirq number, and NULL if there was no
+  mapping.
+- irq_find_mapping() returns a Linux IRQ number for a given domain and
+  hwirq number, and 0 if there was no mapping
+- irq_linear_revmap() is now identical to irq_find_mapping(), and is
+  deprecated
+- generic_handle_domain_irq() handles an interrupt described by a
+  domain and a hwirq number
+- handle_domain_irq() does the same thing for root interrupt
+  controllers and deals with the set_irq_reg()/irq_enter() sequences
+  that most architecture requires
+
+Note that irq domain lookups must happen in contexts that are
+compatible with a RCU read-side critical section.
 
 The irq_create_mapping() function must be called *atleast once*
 before any call to irq_find_mapping(), lest the descriptor will not
@@ -137,7 +153,9 @@ required.  Calling irq_create_direct_mapping() will allocate a Linux
 IRQ number and call the .map() callback so that driver can program the
 Linux IRQ number into the hardware.
 
-Most drivers cannot use this mapping.
+Most drivers cannot use this mapping, and it is now gated on the
+CONFIG_IRQ_DOMAIN_NOMAP option. Please refrain from introducing new
+users of this API.
 
 Legacy
 ------
@@ -157,6 +175,10 @@ for IRQ numbers that are passed to struct device registrations.  In that
 case the Linux IRQ numbers cannot be dynamically assigned and the legacy
 mapping should be used.
 
+As the name implies, the *_legacy() functions are deprecated and only
+exist to ease the support of ancient platforms. No new users should be
+added.
+
 The legacy map assumes a contiguous range of IRQ numbers has already
 been allocated for the controller and that the IRQ number can be
 calculated by adding a fixed offset to the hwirq number, and
-- 
2.30.2


      parent reply	other threads:[~2021-08-02 16:57 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02 16:26 [PATCH v2 00/14][treewide] irqdomain: Simplify interrupt handling Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 01/14] gpio: Bulk conversion to generic_handle_domain_irq() Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 02/14] pinctrl: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 03/14] PCI: " Marc Zyngier
2021-08-02 16:59   ` Bjorn Helgaas
2021-08-02 16:26 ` [PATCH v2 04/14] mfd: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 05/14] gpu: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 06/14] SH: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 07/14] ARM: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 08/14] mips: " Marc Zyngier
2021-08-05  9:10   ` Thomas Bogendoerfer
2021-08-02 16:26 ` [PATCH v2 09/14] arc: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 10/14] xtensa: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 11/14] nios2: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 12/14] powerpc: " Marc Zyngier
2021-08-02 16:26 ` [PATCH v2 13/14] EDAC/altera: Convert " Marc Zyngier
2021-08-02 16:26 ` Marc Zyngier [this message]

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