path: root/Documentation/clk.txt
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2014-05-12clk: Improve clk_ops documentationGeert Uytterhoeven1-5/+11
General: - Add parameter names to .round_rate() and .set_rate(). Documentation/clk.txt: - Add missing parameter for .set_rate(), - Add missing .debug_init(). include/linux/clk-provider.h: - Add parent rate documentation for .round_rate(), - Reorder documentation to match implementation order, - Add missing documentation for .init(). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Mike Turquette <mturquette@linaro.org>
2014-03-19Documentation: clk: Add locking documentationLaurent Pinchart1-0/+34
Briefly document the common clock framework locking scheme from a clock driver point of view. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
2014-01-16clk: Add set_rate_and_parent() opStephen Boyd1-0/+3
Some of Qualcomm's clocks can change their parent and rate at the same time with a single register write. Add support for this hardware to the common clock framework by adding a new set_rate_and_parent() op. When the clock framework determines that both the parent and the rate are going to change during clk_set_rate() it will call the .set_rate_and_parent() op if available and fall back to calling .set_parent() followed by .set_rate() otherwise. Reviewed-by: James Hogan <james.hogan@imgtec.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Mike Turquette <mturquette@linaro.org>
2013-12-22clk: add clk accuracy retrieval supportBoris BREZILLON1-0/+4
The clock accuracy is expressed in ppb (parts per billion) and represents the possible clock drift. Say you have a clock (e.g. an oscillator) which provides a fixed clock of 20MHz with an accuracy of +- 20Hz. This accuracy expressed in ppb is 20Hz/20MHz = 1000 ppb (or 1 ppm). Clock users may need the clock accuracy information in order to choose the best clock (the one with the best accuracy) across several available clocks. This patch adds clk accuracy retrieval support for common clk framework by means of a new function called clk_get_accuracy. This function returns the given clock accuracy expressed in ppb. In order to get the clock accuracy, this implementation adds one callback called recalc_accuracy to the clk_ops structure. This callback is given the parent clock accuracy (if the clock is not a root clock) and should recalculate the given clock accuracy. This callback is optional and may be implemented if the clock is not a perfect clock (accuracy != 0 ppb). Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
2013-08-19clk: add support for clock reparent on set_rateJames Hogan1-20/+26
Add core support to allow clock implementations to select the best parent clock when rounding a rate, e.g. the one which can provide the closest clock rate to that requested. This is by way of adding a new clock op, determine_rate(), which is like round_rate() but has an extra parameter to allow the clock implementation to optionally select a different parent clock. The core then takes care of reparenting the clock when setting the rate. The parent change takes place with the help of some new private data members. struct clk::new_parent specifies a clock's new parent (NULL indicates no change), and struct clk::new_child specifies a clock's new child (whose new_parent member points back to it). The purpose of these are to allow correct walking of the future tree for notifications prior to actually reparenting any clocks, specifically to skip child clocks who are being reparented to another clock (they will be notified via the new parent), and to include any new child clock. These pointers are set by clk_calc_subtree(), and the new_child pointer gets cleared when a child is actually reparented to avoid duplicate POST_RATE_CHANGE notifications. Each place where round_rate() is called, determine_rate() is checked first and called in preference. This restructures a few of the call sites to simplify the logic into if/else blocks. Signed-off-by: James Hogan <james.hogan@imgtec.com> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Mike Turquette <mturquette@linaro.org> Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Mike Turquette <mturquette@linaro.org>
2013-06-10doc: clk: Fix incorrect wordingSachin Kamat1-1/+1
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Acked-by: Rob Landley <rob@landley.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2013-04-27clk: add clk_ignore_unused option to keep boot clocks onOlof Johansson1-0/+11
This is primarily useful when there's a driver that doesn't claim clocks properly, but the bootloader leaves them on. It's not expected to be used in normal cases, but for bringup and debug it's very useful to have the option to not gate unclaimed clocks that are still on. Signed-off-by: Olof Johansson <olof@lixom.net> Signed-off-by: Mike Turquette <mturquette@linaro.org> [mturquette@linaro.org: fixed up trivial merge issue]
2013-03-21documentation: clk: fix couple of misspellingEduardo Valentin1-2/+2
Correcting misspelling inside the clk.txt. Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
2012-03-16Documentation: common clk APIMike Turquette1-0/+233
Provide documentation for the common clk structures and APIs. This code can be found in drivers/clk/ and include/linux/clk*.h. Signed-off-by: Mike Turquette <mturquette@linaro.org> Signed-off-by: Mike Turquette <mturquette@ti.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Cc: Russell King <linux@arm.linux.org.uk> Cc: Jeremy Kerr <jeremy.kerr@canonical.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arnd Bergman <arnd.bergmann@linaro.org> Cc: Paul Walmsley <paul@pwsan.com> Cc: Shawn Guo <shawn.guo@freescale.com> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Richard Zhao <richard.zhao@linaro.org> Cc: Saravana Kannan <skannan@codeaurora.org> Cc: Magnus Damm <magnus.damm@gmail.com> Cc: Rob Herring <rob.herring@calxeda.com> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Linus Walleij <linus.walleij@stericsson.com> Cc: Stephen Boyd <sboyd@codeaurora.org> Cc: Amit Kucheria <amit.kucheria@linaro.org> Cc: Deepak Saxena <dsaxena@linaro.org> Cc: Grant Likely <grant.likely@secretlab.ca> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

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