cpufreq: powerpc: Add cpufreq driver for Freescale e500mc SoCs

Add cpufreq driver for Freescale e500mc, e5500 and e6500 SoCs
which are capable of changing the CPU frequency dynamically

Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

3 files changed, 391 insertions, 0 deletions

diff --git a/drivers/cpufreq/Kconfig.powerpc b/drivers/cpufreq/Kconfig.powerpc
index 9c926ca0d718..88f629e5a393 100644
--- a/drivers/cpufreq/Kconfig.powerpc
+++ b/drivers/cpufreq/Kconfig.powerpc
@@ -23,3 +23,13 @@ config CPU_FREQ_MAPLE
         help
           This adds support for frequency switching on Maple 970FX
           Evaluation Board and compatible boards (IBM JS2x blades).
+
+config PPC_CORENET_CPUFREQ
+        tristate "CPU frequency scaling driver for Freescale E500MC SoCs"
+        depends on PPC_E500MC && OF && COMMON_CLK
+        select CPU_FREQ_TABLE
+        select CLK_PPC_CORENET
+        help
+          This adds the CPUFreq driver support for Freescale e500mc,
+          e5500 and e6500 series SoCs which are capable of changing
+          the CPU's frequency dynamically.
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 315b9231feb1..c956094ccc39 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -79,6 +79,7 @@ obj-$(CONFIG_CPU_FREQ_CBE)		+= ppc-cbe-cpufreq.o
 ppc-cbe-cpufreq-y                       += ppc_cbe_cpufreq_pervasive.o ppc_cbe_cpufreq.o
 obj-$(CONFIG_CPU_FREQ_CBE_PMI)          += ppc_cbe_cpufreq_pmi.o
 obj-$(CONFIG_CPU_FREQ_MAPLE)            += maple-cpufreq.o
+obj-$(CONFIG_PPC_CORENET_CPUFREQ)   += ppc-corenet-cpufreq.o
 
 ##################################################################################
 # Other platform drivers
diff --git a/drivers/cpufreq/ppc-corenet-cpufreq.c b/drivers/cpufreq/ppc-corenet-cpufreq.c
new file mode 100644
index 000000000000..3cae4529f959
--- /dev/null
+++ b/drivers/cpufreq/ppc-corenet-cpufreq.c
@@ -0,0 +1,380 @@
+/*
+ * Copyright 2013 Freescale Semiconductor, Inc.
+ *
+ * CPU Frequency Scaling driver for Freescale PowerPC corenet SoCs.
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/cpufreq.h>
+#include <linux/errno.h>
+#include <sysdev/fsl_soc.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+
+/**
+ * struct cpu_data - per CPU data struct
+ * @clk: the clk of CPU
+ * @parent: the parent node of cpu clock
+ * @table: frequency table
+ */
+struct cpu_data {
+        struct clk *clk;
+        struct device_node *parent;
+        struct cpufreq_frequency_table *table;
+};
+
+/**
+ * struct soc_data - SoC specific data
+ * @freq_mask: mask the disallowed frequencies
+ * @flag: unique flags
+ */
+struct soc_data {
+        u32 freq_mask[4];
+        u32 flag;
+};
+
+#define FREQ_MASK       1
+/* see hardware specification for the allowed frqeuencies */
+static const struct soc_data sdata[] = {
+        { /* used by p2041 and p3041 */
+                .freq_mask = {0x8, 0x8, 0x2, 0x2},
+                .flag = FREQ_MASK,
+        },
+        { /* used by p5020 */
+                .freq_mask = {0x8, 0x2},
+                .flag = FREQ_MASK,
+        },
+        { /* used by p4080, p5040 */
+                .freq_mask = {0},
+                .flag = 0,
+        },
+};
+
+/*
+ * the minimum allowed core frequency, in Hz
+ * for chassis v1.0, >= platform frequency
+ * for chassis v2.0, >= platform frequency / 2
+ */
+static u32 min_cpufreq;
+static const u32 *fmask;
+
+/* serialize frequency changes  */
+static DEFINE_MUTEX(cpufreq_lock);
+static DEFINE_PER_CPU(struct cpu_data *, cpu_data);
+
+/* cpumask in a cluster */
+static DEFINE_PER_CPU(cpumask_var_t, cpu_mask);
+
+#ifndef CONFIG_SMP
+static inline const struct cpumask *cpu_core_mask(int cpu)
+{
+        return cpumask_of(0);
+}
+#endif
+
+static unsigned int corenet_cpufreq_get_speed(unsigned int cpu)
+{
+        struct cpu_data *data = per_cpu(cpu_data, cpu);
+
+        return clk_get_rate(data->clk) / 1000;
+}
+
+/* reduce the duplicated frequencies in frequency table */
+static void freq_table_redup(struct cpufreq_frequency_table *freq_table,
+                int count)
+{
+        int i, j;
+
+        for (i = 1; i < count; i++) {
+                for (j = 0; j < i; j++) {
+                        if (freq_table[j].frequency == CPUFREQ_ENTRY_INVALID ||
+                                        freq_table[j].frequency !=
+                                        freq_table[i].frequency)
+                                continue;
+
+                        freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
+                        break;
+                }
+        }
+}
+
+/* sort the frequencies in frequency table in descenting order */
+static void freq_table_sort(struct cpufreq_frequency_table *freq_table,
+                int count)
+{
+        int i, j, ind;
+        unsigned int freq, max_freq;
+        struct cpufreq_frequency_table table;
+        for (i = 0; i < count - 1; i++) {
+                max_freq = freq_table[i].frequency;
+                ind = i;
+                for (j = i + 1; j < count; j++) {
+                        freq = freq_table[j].frequency;
+                        if (freq == CPUFREQ_ENTRY_INVALID ||
+                                        freq <= max_freq)
+                                continue;
+                        ind = j;
+                        max_freq = freq;
+                }
+
+                if (ind != i) {
+                        /* exchange the frequencies */
+                        table.driver_data = freq_table[i].driver_data;
+                        table.frequency = freq_table[i].frequency;
+                        freq_table[i].driver_data = freq_table[ind].driver_data;
+                        freq_table[i].frequency = freq_table[ind].frequency;
+                        freq_table[ind].driver_data = table.driver_data;
+                        freq_table[ind].frequency = table.frequency;
+                }
+        }
+}
+
+static int corenet_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+        struct device_node *np;
+        int i, count, ret;
+        u32 freq, mask;
+        struct clk *clk;
+        struct cpufreq_frequency_table *table;
+        struct cpu_data *data;
+        unsigned int cpu = policy->cpu;
+
+        np = of_get_cpu_node(cpu, NULL);
+        if (!np)
+                return -ENODEV;
+
+        data = kzalloc(sizeof(*data), GFP_KERNEL);
+        if (!data) {
+                pr_err("%s: no memory\n", __func__);
+                goto err_np;
+        }
+
+        data->clk = of_clk_get(np, 0);
+        if (IS_ERR(data->clk)) {
+                pr_err("%s: no clock information\n", __func__);
+                goto err_nomem2;
+        }
+
+        data->parent = of_parse_phandle(np, "clocks", 0);
+        if (!data->parent) {
+                pr_err("%s: could not get clock information\n", __func__);
+                goto err_nomem2;
+        }
+
+        count = of_property_count_strings(data->parent, "clock-names");
+        table = kcalloc(count + 1, sizeof(*table), GFP_KERNEL);
+        if (!table) {
+                pr_err("%s: no memory\n", __func__);
+                goto err_node;
+        }
+
+        if (fmask)
+                mask = fmask[get_hard_smp_processor_id(cpu)];
+        else
+                mask = 0x0;
+
+        for (i = 0; i < count; i++) {
+                clk = of_clk_get(data->parent, i);
+                freq = clk_get_rate(clk);
+                /*
+                 * the clock is valid if its frequency is not masked
+                 * and large than minimum allowed frequency.
+                 */
+                if (freq < min_cpufreq || (mask & (1 << i)))
+                        table[i].frequency = CPUFREQ_ENTRY_INVALID;
+                else
+                        table[i].frequency = freq / 1000;
+                table[i].driver_data = i;
+        }
+        freq_table_redup(table, count);
+        freq_table_sort(table, count);
+        table[i].frequency = CPUFREQ_TABLE_END;
+
+        /* set the min and max frequency properly */
+        ret = cpufreq_frequency_table_cpuinfo(policy, table);
+        if (ret) {
+                pr_err("invalid frequency table: %d\n", ret);
+                goto err_nomem1;
+        }
+
+        data->table = table;
+        per_cpu(cpu_data, cpu) = data;
+
+        /* update ->cpus if we have cluster, no harm if not */
+        cpumask_copy(policy->cpus, per_cpu(cpu_mask, cpu));
+        for_each_cpu(i, per_cpu(cpu_mask, cpu))
+                per_cpu(cpu_data, i) = data;
+
+        policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
+        policy->cur = corenet_cpufreq_get_speed(policy->cpu);
+
+        cpufreq_frequency_table_get_attr(table, cpu);
+        of_node_put(np);
+
+        return 0;
+
+err_nomem1:
+        kfree(table);
+err_node:
+        of_node_put(data->parent);
+err_nomem2:
+        per_cpu(cpu_data, cpu) = NULL;
+        kfree(data);
+err_np:
+        of_node_put(np);
+
+        return -ENODEV;
+}
+
+static int __exit corenet_cpufreq_cpu_exit(struct cpufreq_policy *policy)
+{
+        struct cpu_data *data = per_cpu(cpu_data, policy->cpu);
+        unsigned int cpu;
+
+        cpufreq_frequency_table_put_attr(policy->cpu);
+        of_node_put(data->parent);
+        kfree(data->table);
+        kfree(data);
+
+        for_each_cpu(cpu, per_cpu(cpu_mask, policy->cpu))
+                per_cpu(cpu_data, cpu) = NULL;
+
+        return 0;
+}
+
+static int corenet_cpufreq_verify(struct cpufreq_policy *policy)
+{
+        struct cpufreq_frequency_table *table =
+                per_cpu(cpu_data, policy->cpu)->table;
+
+        return cpufreq_frequency_table_verify(policy, table);
+}
+
+static int corenet_cpufreq_target(struct cpufreq_policy *policy,
+                unsigned int target_freq, unsigned int relation)
+{
+        struct cpufreq_freqs freqs;
+        unsigned int new;
+        struct clk *parent;
+        int ret;
+        struct cpu_data *data = per_cpu(cpu_data, policy->cpu);
+
+        cpufreq_frequency_table_target(policy, data->table,
+                        target_freq, relation, &new);
+
+        if (policy->cur == data->table[new].frequency)
+                return 0;
+
+        freqs.old = policy->cur;
+        freqs.new = data->table[new].frequency;
+
+        mutex_lock(&cpufreq_lock);
+        cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
+
+        parent = of_clk_get(data->parent, data->table[new].driver_data);
+        ret = clk_set_parent(data->clk, parent);
+        if (ret)
+                freqs.new = freqs.old;
+
+        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
+        mutex_unlock(&cpufreq_lock);
+
+        return ret;
+}
+
+static struct freq_attr *corenet_cpufreq_attr[] = {
+        &cpufreq_freq_attr_scaling_available_freqs,
+        NULL,
+};
+
+static struct cpufreq_driver ppc_corenet_cpufreq_driver = {
+        .name           = "ppc_cpufreq",
+        .owner          = THIS_MODULE,
+        .flags          = CPUFREQ_CONST_LOOPS,
+        .init           = corenet_cpufreq_cpu_init,
+        .exit           = __exit_p(corenet_cpufreq_cpu_exit),
+        .verify         = corenet_cpufreq_verify,
+        .target         = corenet_cpufreq_target,
+        .get            = corenet_cpufreq_get_speed,
+        .attr           = corenet_cpufreq_attr,
+};
+
+static const struct of_device_id node_matches[] __initdata = {
+        { .compatible = "fsl,p2041-clockgen", .data = &sdata[0], },
+        { .compatible = "fsl,p3041-clockgen", .data = &sdata[0], },
+        { .compatible = "fsl,p5020-clockgen", .data = &sdata[1], },
+        { .compatible = "fsl,p4080-clockgen", .data = &sdata[2], },
+        { .compatible = "fsl,p5040-clockgen", .data = &sdata[2], },
+        { .compatible = "fsl,qoriq-clockgen-2.0", },
+        {}
+};
+
+static int __init ppc_corenet_cpufreq_init(void)
+{
+        int ret;
+        struct device_node  *np;
+        const struct of_device_id *match;
+        const struct soc_data *data;
+        unsigned int cpu;
+
+        np = of_find_matching_node(NULL, node_matches);
+        if (!np)
+                return -ENODEV;
+
+        for_each_possible_cpu(cpu) {
+                if (!alloc_cpumask_var(&per_cpu(cpu_mask, cpu), GFP_KERNEL))
+                        goto err_mask;
+                cpumask_copy(per_cpu(cpu_mask, cpu), cpu_core_mask(cpu));
+        }
+
+        match = of_match_node(node_matches, np);
+        data = match->data;
+        if (data) {
+                if (data->flag)
+                        fmask = data->freq_mask;
+                min_cpufreq = fsl_get_sys_freq();
+        } else {
+                min_cpufreq = fsl_get_sys_freq() / 2;
+        }
+
+        of_node_put(np);
+
+        ret = cpufreq_register_driver(&ppc_corenet_cpufreq_driver);
+        if (!ret)
+                pr_info("Freescale PowerPC corenet CPU frequency scaling driver\n");
+
+        return ret;
+
+err_mask:
+        for_each_possible_cpu(cpu)
+                free_cpumask_var(per_cpu(cpu_mask, cpu));
+
+        return -ENOMEM;
+}
+module_init(ppc_corenet_cpufreq_init);
+
+static void __exit ppc_corenet_cpufreq_exit(void)
+{
+        unsigned int cpu;
+
+        for_each_possible_cpu(cpu)
+                free_cpumask_var(per_cpu(cpu_mask, cpu));
+
+        cpufreq_unregister_driver(&ppc_corenet_cpufreq_driver);
+}
+module_exit(ppc_corenet_cpufreq_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Tang Yuantian <Yuantian.Tang@freescale.com>");
+MODULE_DESCRIPTION("cpufreq driver for Freescale e500mc series SoCs");