cpufreq: Implement light weight ->target_index() routine

Currently, the prototype of cpufreq_drivers target routines is:

int target(struct cpufreq_policy *policy, unsigned int target_freq,
		unsigned int relation);

And most of the drivers call cpufreq_frequency_table_target() to get a valid
index of their frequency table which is closest to the target_freq. And they
don't use target_freq and relation after that.

So, it makes sense to just do this work in cpufreq core before calling
cpufreq_frequency_table_target() and simply pass index instead. But this can be
done only with drivers which expose their frequency table with cpufreq core. For
others we need to stick with the old prototype of target() until those drivers
are converted to expose frequency tables.

This patch implements the new light weight prototype for target_index() routine.
It looks like this:

int target_index(struct cpufreq_policy *policy, unsigned int index);

CPUFreq core will call cpufreq_frequency_table_target() before calling this
routine and pass index to it. Because CPUFreq core now requires to call routines
present in freq_table.c CONFIG_CPU_FREQ_TABLE must be enabled all the time.

This also marks target() interface as deprecated. So, that new drivers avoid
using it. And Documentation is updated accordingly.

It also converts existing .target() to newly defined light weight
.target_index() routine for many driver.

Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Russell King <linux@arm.linux.org.uk>
Acked-by: David S. Miller <davem@davemloft.net>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rjw@rjwysocki.net>
diff --git a/drivers/cpufreq/elanfreq.c b/drivers/cpufreq/elanfreq.c
index d91a645..4ab4153 100644
--- a/drivers/cpufreq/elanfreq.c
+++ b/drivers/cpufreq/elanfreq.c
@@ -105,20 +105,8 @@
 }
 
 
-/**
- *	elanfreq_set_cpu_frequency: Change the CPU core frequency
- *	@cpu: cpu number
- *	@freq: frequency in kHz
- *
- *	This function takes a frequency value and changes the CPU frequency
- *	according to this. Note that the frequency has to be checked by
- *	elanfreq_validatespeed() for correctness!
- *
- *	There is no return value.
- */
-
-static void elanfreq_set_cpu_state(struct cpufreq_policy *policy,
-		unsigned int state)
+static int elanfreq_target(struct cpufreq_policy *policy,
+			    unsigned int state)
 {
 	struct cpufreq_freqs    freqs;
 
@@ -162,25 +150,9 @@
 	local_irq_enable();
 
 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
-};
-
-
-static int elanfreq_target(struct cpufreq_policy *policy,
-			    unsigned int target_freq,
-			    unsigned int relation)
-{
-	unsigned int newstate = 0;
-
-	if (cpufreq_frequency_table_target(policy, &elanfreq_table[0],
-				target_freq, relation, &newstate))
-		return -EINVAL;
-
-	elanfreq_set_cpu_state(policy, newstate);
 
 	return 0;
 }
-
-
 /*
  *	Module init and exit code
  */
@@ -237,7 +209,7 @@
 static struct cpufreq_driver elanfreq_driver = {
 	.get		= elanfreq_get_cpu_frequency,
 	.verify		= cpufreq_generic_frequency_table_verify,
-	.target		= elanfreq_target,
+	.target_index	= elanfreq_target,
 	.init		= elanfreq_cpu_init,
 	.exit		= cpufreq_generic_exit,
 	.name		= "elanfreq",