cpufreq: Add and use cpufreq_for_each_{valid_,}entry_idx()

Pointer subtraction is slow and tedious. Therefore, replace all instances
where cpufreq_for_each_{valid_,}entry loops contained such substractions
with an iteration macro providing an index to the frequency_table entry.

Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Link: http://lkml.kernel.org/r/20180120020237.GM13338@ZenIV.linux.org.uk
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

8 files changed, 100 insertions, 63 deletions

diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index 434c49cc7330..61546ac578d6 100644
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -291,3 +291,7 @@ For example:
                 /* Do something with pos */
                 pos->frequency = ...
         }
+
+If you need to work with the position of pos within driver_freq_table,
+do not subtract the pointers, as it is quite costly. Instead, use the
+macros cpufreq_for_each_entry_idx() and cpufreq_for_each_valid_entry_idx().
diff --git a/drivers/cpufreq/exynos5440-cpufreq.c b/drivers/cpufreq/exynos5440-cpufreq.c
index b6b369c22272..932caa386ece 100644
--- a/drivers/cpufreq/exynos5440-cpufreq.c
+++ b/drivers/cpufreq/exynos5440-cpufreq.c
@@ -115,10 +115,10 @@ static struct cpufreq_freqs freqs;
 static int init_div_table(void)
 {
         struct cpufreq_frequency_table *pos, *freq_tbl = dvfs_info->freq_table;
-        unsigned int tmp, clk_div, ema_div, freq, volt_id;
+        unsigned int tmp, clk_div, ema_div, freq, volt_id, idx;
         struct dev_pm_opp *opp;
 
-        cpufreq_for_each_entry(pos, freq_tbl) {
+        cpufreq_for_each_entry_idx(pos, freq_tbl, idx) {
                 opp = dev_pm_opp_find_freq_exact(dvfs_info->dev,
                                         pos->frequency * 1000, true);
                 if (IS_ERR(opp)) {
@@ -154,8 +154,7 @@ static int init_div_table(void)
                 tmp = (clk_div | ema_div | (volt_id << P0_7_VDD_SHIFT)
                         | ((freq / FREQ_UNIT) << P0_7_FREQ_SHIFT));
 
-                __raw_writel(tmp, dvfs_info->base + XMU_PMU_P0_7 + 4 *
-                                                (pos - freq_tbl));
+                __raw_writel(tmp, dvfs_info->base + XMU_PMU_P0_7 + 4 * idx);
                 dev_pm_opp_put(opp);
         }
 
diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index 3bbbf9e6960c..6d007f824ca7 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c
@@ -143,10 +143,9 @@ int cpufreq_table_index_unsorted(struct cpufreq_policy *policy,
                 break;
         }
 
-        cpufreq_for_each_valid_entry(pos, table) {
+        cpufreq_for_each_valid_entry_idx(pos, table, i) {
                 freq = pos->frequency;
 
-                i = pos - table;
                 if ((freq < policy->min) || (freq > policy->max))
                         continue;
                 if (freq == target_freq) {
@@ -211,15 +210,16 @@ int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy,
                 unsigned int freq)
 {
         struct cpufreq_frequency_table *pos, *table = policy->freq_table;
+        int idx;
 
         if (unlikely(!table)) {
                 pr_debug("%s: Unable to find frequency table\n", __func__);
                 return -ENOENT;
         }
 
-        cpufreq_for_each_valid_entry(pos, table)
+        cpufreq_for_each_valid_entry_idx(pos, table, idx)
                 if (pos->frequency == freq)
-                        return pos - table;
+                        return idx;
 
         return -EINVAL;
 }
diff --git a/drivers/cpufreq/longhaul.c b/drivers/cpufreq/longhaul.c
index 5faa37c5b091..942632a27b50 100644
--- a/drivers/cpufreq/longhaul.c
+++ b/drivers/cpufreq/longhaul.c
@@ -600,7 +600,7 @@ static void longhaul_setup_voltagescaling(void)
         /* Calculate kHz for one voltage step */
         kHz_step = (highest_speed - min_vid_speed) / numvscales;
 
-        cpufreq_for_each_entry(freq_pos, longhaul_table) {
+        cpufreq_for_each_entry_idx(freq_pos, longhaul_table, j) {
                 speed = freq_pos->frequency;
                 if (speed > min_vid_speed)
                         pos = (speed - min_vid_speed) / kHz_step + minvid.pos;
@@ -609,7 +609,7 @@ static void longhaul_setup_voltagescaling(void)
                 freq_pos->driver_data |= mV_vrm_table[pos] << 8;
                 vid = vrm_mV_table[mV_vrm_table[pos]];
                 pr_info("f: %d kHz, index: %d, vid: %d mV\n",
-                        speed, (int)(freq_pos - longhaul_table), vid.mV);
+                        speed, j, vid.mV);
         }
 
         can_scale_voltage = 1;
diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
index b257fc7d5204..75dfbd2a58ea 100644
--- a/drivers/cpufreq/pasemi-cpufreq.c
+++ b/drivers/cpufreq/pasemi-cpufreq.c
@@ -139,7 +139,7 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
         struct cpufreq_frequency_table *pos;
         const u32 *max_freqp;
         u32 max_freq;
-        int cur_astate;
+        int cur_astate, idx;
         struct resource res;
         struct device_node *cpu, *dn;
         int err = -ENODEV;
@@ -198,9 +198,9 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
         pr_debug("initializing frequency table\n");
 
         /* initialize frequency table */
-        cpufreq_for_each_entry(pos, pas_freqs) {
+        cpufreq_for_each_entry_idx(pos, pas_freqs, idx) {
                 pos->frequency = get_astate_freq(pos->driver_data) * 100000;
-                pr_debug("%d: %d\n", (int)(pos - pas_freqs), pos->frequency);
+                pr_debug("%d: %d\n", idx, pos->frequency);
         }
 
         cur_astate = get_cur_astate(policy->cpu);
diff --git a/drivers/sh/clk/core.c b/drivers/sh/clk/core.c
index 92863e3818e5..9475353f49d6 100644
--- a/drivers/sh/clk/core.c
+++ b/drivers/sh/clk/core.c
@@ -197,10 +197,11 @@ int clk_rate_table_find(struct clk *clk,
                         unsigned long rate)
 {
         struct cpufreq_frequency_table *pos;
+        int idx;
 
-        cpufreq_for_each_valid_entry(pos, freq_table)
+        cpufreq_for_each_valid_entry_idx(pos, freq_table, idx)
                 if (pos->frequency == rate)
-                        return pos - freq_table;
+                        return idx;
 
         return -ENOENT;
 }
diff --git a/drivers/staging/irda/drivers/sh_sir.c b/drivers/staging/irda/drivers/sh_sir.c
index fede6864c737..0d0687cc454a 100644
--- a/drivers/staging/irda/drivers/sh_sir.c
+++ b/drivers/staging/irda/drivers/sh_sir.c
@@ -226,7 +226,7 @@ static u32 sh_sir_find_sclk(struct clk *irda_clk)
         clk_put(pclk);
 
         /* IrDA can not set over peripheral_clk */
-        cpufreq_for_each_valid_entry(pos, freq_table) {
+        cpufreq_for_each_valid_entry_idx(pos, freq_table, index) {
                 u32 freq = pos->frequency;
 
                 /* IrDA should not over peripheral_clk */
@@ -236,7 +236,7 @@ static u32 sh_sir_find_sclk(struct clk *irda_clk)
                 tmp = freq % SCLK_BASE;
                 if (tmp < min) {
                         min = tmp;
-                        index = pos - freq_table;
+                        break;
                 }
         }
 
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 065f3a8eb486..21e8d248d956 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -629,6 +629,18 @@ static inline void dev_pm_opp_free_cpufreq_table(struct device *dev,
         for (pos = table; pos->frequency != CPUFREQ_TABLE_END; pos++)
 
 /*
+ * cpufreq_for_each_entry_idx - iterate over a cpufreq_frequency_table
+ *      with index
+ * @pos:        the cpufreq_frequency_table * to use as a loop cursor.
+ * @table:      the cpufreq_frequency_table * to iterate over.
+ * @idx:        the table entry currently being processed
+ */
+
+#define cpufreq_for_each_entry_idx(pos, table, idx)     \
+        for (pos = table, idx = 0; pos->frequency != CPUFREQ_TABLE_END; \
+                pos++, idx++)
+
+/*
  * cpufreq_for_each_valid_entry -     iterate over a cpufreq_frequency_table
  *      excluding CPUFREQ_ENTRY_INVALID frequencies.
  * @pos:        the cpufreq_frequency_table * to use as a loop cursor.
@@ -641,6 +653,21 @@ static inline void dev_pm_opp_free_cpufreq_table(struct device *dev,
                         continue;                                       \
                 else
 
+/*
+ * cpufreq_for_each_valid_entry_idx -     iterate with index over a cpufreq
+ *      frequency_table excluding CPUFREQ_ENTRY_INVALID frequencies.
+ * @pos:        the cpufreq_frequency_table * to use as a loop cursor.
+ * @table:      the cpufreq_frequency_table * to iterate over.
+ * @idx:        the table entry currently being processed
+ */
+
+#define cpufreq_for_each_valid_entry_idx(pos, table, idx)               \
+        cpufreq_for_each_entry_idx(pos, table, idx)                     \
+                if (pos->frequency == CPUFREQ_ENTRY_INVALID)            \
+                        continue;                                       \
+                else
+
+
 int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
                                     struct cpufreq_frequency_table *table);
 
@@ -667,19 +694,20 @@ static inline int cpufreq_table_find_index_al(struct cpufreq_policy *policy,
                                               unsigned int target_freq)
 {
         struct cpufreq_frequency_table *table = policy->freq_table;
-        struct cpufreq_frequency_table *pos, *best = table - 1;
+        struct cpufreq_frequency_table *pos;
         unsigned int freq;
+        int idx, best = -1;
 
-        cpufreq_for_each_valid_entry(pos, table) {
+        cpufreq_for_each_valid_entry_idx(pos, table, idx) {
                 freq = pos->frequency;
 
                 if (freq >= target_freq)
-                        return pos - table;
+                        return idx;
 
-                best = pos;
+                best = idx;
         }
 
-        return best - table;
+        return best;
 }
 
 /* Find lowest freq at or above target in a table in descending order */
@@ -687,28 +715,29 @@ static inline int cpufreq_table_find_index_dl(struct cpufreq_policy *policy,
                                               unsigned int target_freq)
 {
         struct cpufreq_frequency_table *table = policy->freq_table;
-        struct cpufreq_frequency_table *pos, *best = table - 1;
+        struct cpufreq_frequency_table *pos;
         unsigned int freq;
+        int idx, best = -1;
 
-        cpufreq_for_each_valid_entry(pos, table) {
+        cpufreq_for_each_valid_entry_idx(pos, table, idx) {
                 freq = pos->frequency;
 
                 if (freq == target_freq)
-                        return pos - table;
+                        return idx;
 
                 if (freq > target_freq) {
-                        best = pos;
+                        best = idx;
                         continue;
                 }
 
                 /* No freq found above target_freq */
-                if (best == table - 1)
-                        return pos - table;
+                if (best == -1)
+                        return idx;
 
-                return best - table;
+                return best;
         }
 
-        return best - table;
+        return best;
 }
 
 /* Works only on sorted freq-tables */
@@ -728,28 +757,29 @@ static inline int cpufreq_table_find_index_ah(struct cpufreq_policy *policy,
                                               unsigned int target_freq)
 {
         struct cpufreq_frequency_table *table = policy->freq_table;
-        struct cpufreq_frequency_table *pos, *best = table - 1;
+        struct cpufreq_frequency_table *pos;
         unsigned int freq;
+        int idx, best = -1;
 
-        cpufreq_for_each_valid_entry(pos, table) {
+        cpufreq_for_each_valid_entry_idx(pos, table, idx) {
                 freq = pos->frequency;
 
                 if (freq == target_freq)
-                        return pos - table;
+                        return idx;
 
                 if (freq < target_freq) {
-                        best = pos;
+                        best = idx;
                         continue;
                 }
 
                 /* No freq found below target_freq */
-                if (best == table - 1)
-                        return pos - table;
+                if (best == -1)
+                        return idx;
 
-                return best - table;
+                return best;
         }
 
-        return best - table;
+        return best;
 }
 
 /* Find highest freq at or below target in a table in descending order */
@@ -757,19 +787,20 @@ static inline int cpufreq_table_find_index_dh(struct cpufreq_policy *policy,
                                               unsigned int target_freq)
 {
         struct cpufreq_frequency_table *table = policy->freq_table;
-        struct cpufreq_frequency_table *pos, *best = table - 1;
+        struct cpufreq_frequency_table *pos;
         unsigned int freq;
+        int idx, best = -1;
 
-        cpufreq_for_each_valid_entry(pos, table) {
+        cpufreq_for_each_valid_entry_idx(pos, table, idx) {
                 freq = pos->frequency;
 
                 if (freq <= target_freq)
-                        return pos - table;
+                        return idx;
 
-                best = pos;
+                best = idx;
         }
 
-        return best - table;
+        return best;
 }
 
 /* Works only on sorted freq-tables */
@@ -789,32 +820,33 @@ static inline int cpufreq_table_find_index_ac(struct cpufreq_policy *policy,
                                               unsigned int target_freq)
 {
         struct cpufreq_frequency_table *table = policy->freq_table;
-        struct cpufreq_frequency_table *pos, *best = table - 1;
+        struct cpufreq_frequency_table *pos;
         unsigned int freq;
+        int idx, best = -1;
 
-        cpufreq_for_each_valid_entry(pos, table) {
+        cpufreq_for_each_valid_entry_idx(pos, table, idx) {
                 freq = pos->frequency;
 
                 if (freq == target_freq)
-                        return pos - table;
+                        return idx;
 
                 if (freq < target_freq) {
-                        best = pos;
+                        best = idx;
                         continue;
                 }
 
                 /* No freq found below target_freq */
-                if (best == table - 1)
-                        return pos - table;
+                if (best == -1)
+                        return idx;
 
                 /* Choose the closest freq */
-                if (target_freq - best->frequency > freq - target_freq)
-                        return pos - table;
+                if (target_freq - table[best].frequency > freq - target_freq)
+                        return idx;
 
-                return best - table;
+                return best;
         }
 
-        return best - table;
+        return best;
 }
 
 /* Find closest freq to target in a table in descending order */
@@ -822,32 +854,33 @@ static inline int cpufreq_table_find_index_dc(struct cpufreq_policy *policy,
                                               unsigned int target_freq)
 {
         struct cpufreq_frequency_table *table = policy->freq_table;
-        struct cpufreq_frequency_table *pos, *best = table - 1;
+        struct cpufreq_frequency_table *pos;
         unsigned int freq;
+        int idx, best = -1;
 
-        cpufreq_for_each_valid_entry(pos, table) {
+        cpufreq_for_each_valid_entry_idx(pos, table, idx) {
                 freq = pos->frequency;
 
                 if (freq == target_freq)
-                        return pos - table;
+                        return idx;
 
                 if (freq > target_freq) {
-                        best = pos;
+                        best = idx;
                         continue;
                 }
 
                 /* No freq found above target_freq */
-                if (best == table - 1)
-                        return pos - table;
+                if (best == -1)
+                        return idx;
 
                 /* Choose the closest freq */
-                if (best->frequency - target_freq > target_freq - freq)
-                        return pos - table;
+                if (table[best].frequency - target_freq > target_freq - freq)
+                        return idx;
 
-                return best - table;
+                return best;
         }
 
-        return best - table;
+        return best;
 }
 
 /* Works only on sorted freq-tables */