Kevin Hilman had written, on 11/25/2009 05:46 PM, the following: [...] >>> something like this instead: >>> >>> /** >>> * opp_find_freq() >>> * @oppl: OPP list >>> * @freq: Frequency to look for in OPP table >>> * >>> * Look for an enabled OPP with a frequency value matching @freq. >>> * >>> * Returns pointer to OPP entry if match is found, or NULL if no match >>> * found. >>> */ >>> struct omap_opp *opp_find_freq(const struct omap_opp *oppl, u32 freq); >> I did think about it(single function doing multiple things), the >> intention is as follows in reality: >> opp_is_valid : Search only for enabled frequencies >> opp_has_freq : Searches for enabled/disabled frequencies >> >> This is useful for some logic which wants to enable a frequency which >> may have been disabled in the table. now, to retain that >> functionality, >> A) >> /** >> * opp_find_freq() - Find a opp corresponding to frequency >> * @oppl: opp list to search >> * @freq: frequency to loopup in OPP table >> * @enabled: search only enabled frequencies >> * >> * return opp handle corresponding to the frequency found, else >> * return NULL. Search for enabled frequencies if enabled flag >> * is true, else search for disabled frequencies also >> */ >> struct omap_opp *opp_find_freq(const struct omap_opp *oppl, >> unsigned long freq, bool enabled); >> >> This will handle the functionalities that are supported in rev 3. >> >> B) I rename existing functions: >> opp_has_freq ==> opp_is_disabled() >> opp_is_valid ==> opp_is_enabled() >> >> I would still prefer to go with explicit function search APIs.. > > I like (A) here. Ack. I can see it useful if we go to a list iterator at a later point of time. [...] >>> /** >>> * opp_find_freq_rounded() >>> * @oppl: OPP list >>> * @freq: Frequency to look for in OPP table >>> * @rounding: Rounding option: NONE, UP, DOWN >>> * >>> * Look for an OPP with a frequency value matching @freq. If >>> * @rounding != ROUND_NONE, find closest match using rounding. >>> * >>> * Can be used to find exact OPP, or match using given rounding: >>> >>> * @rounding == UP: find next highest frequency >>> * @rounding == DOWN: find next lowest frequency >>> * @rounding == CLOSEST: find closest frequency >>> * >>> * Returns pointer to OPP entry if match is found, or NULL if no match >>> * found (only possible when no rounding is used) >>> */ >>> struct omap_opp *opp_find_freq_rounded(struct omap_opp *oppl, u32 freq, u32 rounding); >>> >>> Looking at the users of the 'higher' and 'lower' OPPs in the current >>> code, I see that SRF tries to use all three one after the other. >>> First it checks for exact match, then for higher, then for lower. >>> This could be replaced simply by doing a 'closest' match. >> hmmm.. I think we are going a full circle here. >> >> /* Search exact frequency */ >> #define OPP_ROUND_NONE (0 << 0) >> /* Search approx frequency */ >> #define OPP_ROUND_CLOSEST (1 << 0) >> /* Search up */ >> #define OPP_ROUND_HIGH (0 << 1) >> /* Search down */ >> #define OPP_ROUND_LOW (1 << 1) >> >> struct omap_opp *opp_find_freq_rounded(struct omap_opp *oppl, >> unsigned long freq, u8 rounding_flag); >> >> Note: the only difference b/w this and opp_find_freq is that >> opp_find_freq will also search for enabled/disabled. >> If I add that here, this is exactly the #1 implementation I did in >> http://marc.info/?l=linux-omap&m=125800489123496&w=2 >> ok, I used bool instead of a #define and added the complexity of using >> enabled flag also: >> >> bool search_higher, bool search_enabled_only, bool exact_search >> >> what you are proposing is that I go back to my implementation #1 and >> remove my bools instead by adding #defines: >> /* Search up */ >> #define OPP_ROUND_ENABLED (0 << 2) >> /* Search down */ >> #define OPP_ROUND_ANY (1 << 2) >> >> would even make the find_freq redundant.. >> >> Now, in your comment in >> http://marc.info/?l=linux-omap&m=125816031406704&w=2 quote:"I think >> all the options to this function make it not terribly >> readable." >> >> Does it become any different now? >> > > Yeah, I still think multiple bools to a function is a readability > problem. Every time you look at a call, you have to look at the > prototype to remember what all the options are. A single bool or flag > is better IMHO. > >> without taking this in, exact searches can be done by specific >> functions and approximate searches by another function.. we go >> generic functions or we go specific functions.. generic comments I >> have been getting is to go specific, hence the v2 and v3 series. > > OK, you're right. I am causing us to go around in circles now, but > we're going around in increasingly smaller circles and hopefully > converging on the target. ;) Yep :) > > So what I propose is having two functions. One for exact matches > (your proposal A above) and one for approximate matches which is > something like my find_freq_rounded(), but should maybe be renamed > something like opp_find_freq_approx() or something. OK - Signed-Off. prototypes again :) Dead functions: opp_has_freq, opp_is_valid, opp_find_freq and other searches. Only two of them remain: (git diff follows) opp_find_freq_approx opp_find_freq_exact [..] >> int __init opp_add(struct omap_opp **oppl, const struct omap_opp_def >> *opp_defs); > > Mostly, but I was thinking of an API for adding a *single* OPP. The > init code would iterate over its opp_def table adding OPPs one at a > time resultingin multiple calls to opp_add(). > > OK, now I'm going around in circles again, but thinking more about his > we probably need your original opp_init() which will create an empty > master list, then repeated calls to opp_add() to add each OPP to the > master list. Opp_init will be a subcase of opp_add. Giving opp_add capabiity to take More than one def is useful for us in the long run: a) You can add bunch of them without list iterator repeating in each and every adding code. b) You can still add a single one if you choose to. c) add to a NULL list == init the list. That does sound implicit to me, but if we want to create a singular function for it alone, then I recommend: lets just have opp_init, then see if we need to add opp_add -> none of the systems are mature enough for us to use it.. I am open either way. > > Also does add need to be __init? Not sure why we would need to add > OPPs after boot time if we have the ability to enable/disable them at > runtime, but just a thought. Removed.. if in case we would like to do an opp_add at some point. > [...] diff --git a/arch/arm/plat-omap/include/plat/opp.h b/arch/arm/plat-omap/include/plat/opp.h new file mode 100644 index 0000000..4a00685 --- /dev/null +++ b/arch/arm/plat-omap/include/plat/opp.h @@ -0,0 +1,184 @@ +/* + * OMAP OPP Interface + * + * Copyright (C) 2009 Texas Instruments Incorporated. + * Nishanth Menon + * Copyright (C) 2009 Deep Root Systems, LLC. + * Kevin Hilman + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#ifndef __ASM_ARM_OMAP_OPP_H +#define __ASM_ARM_OMAP_OPP_H + +/** + * struct omap_opp - OMAP OPP description structure + * @enabled: true/false - marking this OPP as enabled/disabled + * @rate: Frequency in hertz + * @opp_id: (DEPRECATED) opp identifier + * @vsel: Voltage in volt processor level(this usage is + * DEPRECATED to use Voltage in microvolts in future) + * uV = ((vsel * 12.5) + 600) * 1000 + * + * This structure stores the OPP information for a given domain. + * Due to legacy reasons, this structure is currently exposed and + * will soon be removed elsewhere and will only be used as a handle + * from the OPP internal referencing mechanism + */ +struct omap_opp { + bool enabled; + unsigned long rate; + u8 opp_id __deprecated; + u16 vsel; +}; + +/** + * opp_get_voltage() - Gets the voltage corresponding to an opp + * @opp: opp for which voltage has to be returned for + * + * Return voltage in micro volt corresponding to the opp, else + * return 0 + */ +unsigned long opp_get_voltage(const struct omap_opp *opp); + +/** + * opp_get_freq() - Gets the frequency corresponding to an opp + * @opp: opp for which frequency has to be returned for + * + * Return frequency in hertz corresponding to the opp, else + * return 0 + */ +unsigned long opp_get_freq(const struct omap_opp *opp); + +/** + * opp_get_opp_count - Get number of opps enabled in the opp list + * @num: returns the number of opps + * @oppl: opp list + * + * This functions returns the number of opps if there are any OPPs enabled, + * else returns corresponding error value. + */ +int opp_get_opp_count(const struct omap_opp *oppl); + +#define OPP_SEARCH_HIGH (0 << 1) +#define OPP_SEARCH_LOW (1 << 1) +/** + * opp_find_freq_approx() - Search for an approximate freq + * @oppl: starting list + * @freq: start frequency + * @dir_flags: search direction + * OPP_SEARCH_HIGH - search for next highest freq + * OPP_SEARCH_LOW - search for next lowest freq + * + * Search for the higher/lower *enabled* OPP than a starting freq + * from a start opp list. + + * Returns *opp and *freq is populated with the next match, + * else returns NULL + * + * Example usages: + * * print all frequencies in descending order * + * unsigned long freq; + * struct omap_opp *opp; + * for(opp = oppl, freq = ULONG_MAX; opp; + * opp = opp_find_freq_approx(opp, &freq, OPP_SEARCH_LOW)) + * pr_info("%ld ", freq); + * + * * print all frequencies in ascending order * + * unsigned long freq = 0; + * struct omap_opp *opp; + * for(opp = oppl, freq = 0; opp; + * opp = opp_find_freq_approx(opp, &freq, OPP_SEARCH_HIGH)) + * pr_info("%ld ", freq); + * NOTE: if we set freq as ULONG_MAX, we get the highest enabled frequency + * + */ +struct omap_opp *opp_find_freq_approx(struct omap_opp *oppl, + unsigned long *freq, u8 dir_flags); + +/** + * opp_find_freq_exact() - search for an exact frequency + * @oppl: OPP list + * @freq: frequency to search for + * @enabled: enabled/disabled OPP to search for + * + * searches for the match in the opp list and returns handle to the matching + * opp if found, else returns NULL. + * + * Note enabled is a modifier for the search. if enabled=true, then the match is + * for exact matching frequency and is enabled. if true, the match is for exact + * frequency which is disabled. + */ +struct omap_opp *opp_find_freq_exact(struct omap_opp *oppl, + unsigned long freq, bool enabled); + + +/** + * struct omap_opp_def - OMAP OPP Definition + * @enabled: True/false - is this OPP enabled/disabled by default + * @freq: Frequency in hertz corresponding to this OPP + * @u_volt: Nominal voltage in microvolts corresponding to this OPP + * + * OMAP SOCs have a standard set of tuples consisting of frequency and voltage + * pairs that the device will support per voltage domain. This is called + * Operating Points or OPP. The actual definitions of OMAP Operating Points + * varies over silicon within the same family of devices. For a specific + * domain, you can have a set of {frequency, voltage} pairs and this is denoted + * by an array of omap_opp_def. As the kernel boots and more information is + * available, a set of these are activated based on the precise nature of + * device the kernel boots up on. It is interesting to remember that each IP + * which belongs to a voltage domain may define their own set of OPPs on top + * of this - but this is handled by the appropriate driver. + */ +struct omap_opp_def { + bool enabled; + unsigned long freq; + u32 u_volt; +}; + +/** + * opp_add - Add/initialize an OPP table from a table definitions + * @oppl: Returned back to caller as the opp list to reference the OPP + * @opp_defs: Array of omap_opp_def to describe the OPP. This list should be + * 0 terminated. + * + * This function adds the opp definition to an internal opp list and returns + * a handle representing the OPP list. This handle is then used for further + * validation, search, modification operations on the OPP list. + * + * This function returns 0 and the pointer to the allocated list through oppl if + * success, else corresponding error value. Caller should NOT free the oppl. + * opps_defs can be freed after use. + * + * NOTE: caller should assume that on success, oppl is probably populated with + * a new handle and the new handle should be used for further referencing + */ +int opp_add(struct omap_opp **oppl, const struct omap_opp_def *opp_defs); + +/** + * opp_enable - Enable a specific OPP + * @opp: pointer to opp + * + * Enables a provided opp. If the operation is valid, this returns 0, else the + * corresponding error value. + * + * OPP used here is from the the opp_is_valid/opp_has_freq or other search + * functions + */ +int opp_enable(struct omap_opp *opp); + +/** + * opp_disable - Disable a specific OPP + * @opp: pointer to opp + * + * Disables a provided opp. If the operation is valid, this returns 0, else the + * corresponding error value. + * + * OPP used here is from the the opp_is_valid/opp_has_freq or other search + * functions + */ +int opp_disable(struct omap_opp *opp); + +#endif /* __ASM_ARM_OMAP_OPP_H * -- Regards, Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
