cpufreq: bmips-cpufreq: CPUfreq driver for Broadcom's BMIPS SoCs

Add the MIPS CPUfreq driver. This driver currently supports CPUfreq on
BMIPS5xxx-based SoCs.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 15adef473d42c5018782064dc0c88af4efbe73aa..ec040a57458c53741639eea6f9ade1c50010733b 100644 (file)
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -263,6 +263,16 @@ config IA64_ACPI_CPUFREQ
 endif
 
 if MIPS
+config BMIPS_CPUFREQ
+       tristate "BMIPS CPUfreq Driver"
+       help
+         This option adds a CPUfreq driver for BMIPS processors with
+         support for configurable CPU frequency.
+
+         For now, BMIPS5 chips are supported (such as the Broadcom 7425).
+
+         If in doubt, say N.
+
 config LOONGSON2_CPUFREQ
        tristate "Loongson2 CPUFreq Driver"
        help

diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 1e46c3918e7a630647d744549a46c184e5e8fd80..b7b3fc7e4b735f8844a5cb9f5698aa688deb592b 100644 (file)
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -98,6 +98,7 @@ obj-$(CONFIG_POWERNV_CPUFREQ)         += powernv-cpufreq.o
 # Other platform drivers
 obj-$(CONFIG_AVR32_AT32AP_CPUFREQ)     += at32ap-cpufreq.o
 obj-$(CONFIG_BFIN_CPU_FREQ)            += blackfin-cpufreq.o
+obj-$(CONFIG_BMIPS_CPUFREQ)            += bmips-cpufreq.o
 obj-$(CONFIG_CRIS_MACH_ARTPEC3)                += cris-artpec3-cpufreq.o
 obj-$(CONFIG_ETRAXFS)                  += cris-etraxfs-cpufreq.o
 obj-$(CONFIG_IA64_ACPI_CPUFREQ)                += ia64-acpi-cpufreq.o

diff --git a/drivers/cpufreq/bmips-cpufreq.c b/drivers/cpufreq/bmips-cpufreq.c
new file mode 100644 (file)
index 0000000..1653151
--- /dev/null
+++ b/drivers/cpufreq/bmips-cpufreq.c
@@ -0,0 +1,188 @@
+/*
+ * CPU frequency scaling for Broadcom BMIPS SoCs
+ *
+ * Copyright (c) 2017 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/cpufreq.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+
+/* for mips_hpt_frequency */
+#include <asm/time.h>
+
+#define BMIPS_CPUFREQ_PREFIX   "bmips"
+#define BMIPS_CPUFREQ_NAME     BMIPS_CPUFREQ_PREFIX "-cpufreq"
+
+#define TRANSITION_LATENCY     (25 * 1000)     /* 25 us */
+
+#define BMIPS5_CLK_DIV_SET_SHIFT       0x7
+#define BMIPS5_CLK_DIV_SHIFT           0x4
+#define BMIPS5_CLK_DIV_MASK            0xf
+
+enum bmips_type {
+       BMIPS5000,
+       BMIPS5200,
+};
+
+struct cpufreq_compat {
+       const char *compatible;
+       unsigned int bmips_type;
+       unsigned int clk_mult;
+       unsigned int max_freqs;
+};
+
+#define BMIPS(c, t, m, f) { \
+       .compatible = c, \
+       .bmips_type = (t), \
+       .clk_mult = (m), \
+       .max_freqs = (f), \
+}
+
+static struct cpufreq_compat bmips_cpufreq_compat[] = {
+       BMIPS("brcm,bmips5000", BMIPS5000, 8, 4),
+       BMIPS("brcm,bmips5200", BMIPS5200, 8, 4),
+       { }
+};
+
+static struct cpufreq_compat *priv;
+
+static int htp_freq_to_cpu_freq(unsigned int clk_mult)
+{
+       return mips_hpt_frequency * clk_mult / 1000;
+}
+
+static struct cpufreq_frequency_table *
+bmips_cpufreq_get_freq_table(const struct cpufreq_policy *policy)
+{
+       struct cpufreq_frequency_table *table;
+       unsigned long cpu_freq;
+       int i;
+
+       cpu_freq = htp_freq_to_cpu_freq(priv->clk_mult);
+
+       table = kmalloc((priv->max_freqs + 1) * sizeof(*table), GFP_KERNEL);
+       if (!table)
+               return ERR_PTR(-ENOMEM);
+
+       for (i = 0; i < priv->max_freqs; i++) {
+               table[i].frequency = cpu_freq / (1 << i);
+               table[i].driver_data = i;
+       }
+       table[i].frequency = CPUFREQ_TABLE_END;
+
+       return table;
+}
+
+static unsigned int bmips_cpufreq_get(unsigned int cpu)
+{
+       unsigned int div;
+       uint32_t mode;
+
+       switch (priv->bmips_type) {
+       case BMIPS5200:
+       case BMIPS5000:
+               mode = read_c0_brcm_mode();
+               div = ((mode >> BMIPS5_CLK_DIV_SHIFT) & BMIPS5_CLK_DIV_MASK);
+               break;
+       default:
+               div = 0;
+       }
+
+       return htp_freq_to_cpu_freq(priv->clk_mult) / (1 << div);
+}
+
+static int bmips_cpufreq_target_index(struct cpufreq_policy *policy,
+                                     unsigned int index)
+{
+       unsigned int div = policy->freq_table[index].driver_data;
+
+       switch (priv->bmips_type) {
+       case BMIPS5200:
+       case BMIPS5000:
+               change_c0_brcm_mode(BMIPS5_CLK_DIV_MASK << BMIPS5_CLK_DIV_SHIFT,
+                                   (1 << BMIPS5_CLK_DIV_SET_SHIFT) |
+                                   (div << BMIPS5_CLK_DIV_SHIFT));
+               break;
+       default:
+               return -ENOTSUPP;
+       }
+
+       return 0;
+}
+
+static int bmips_cpufreq_exit(struct cpufreq_policy *policy)
+{
+       kfree(policy->freq_table);
+
+       return 0;
+}
+
+static int bmips_cpufreq_init(struct cpufreq_policy *policy)
+{
+       struct cpufreq_frequency_table *freq_table;
+       int ret;
+
+       freq_table = bmips_cpufreq_get_freq_table(policy);
+       if (IS_ERR(freq_table)) {
+               ret = PTR_ERR(freq_table);
+               pr_err("%s: couldn't determine frequency table (%d).\n",
+                       BMIPS_CPUFREQ_NAME, ret);
+               return ret;
+       }
+
+       ret = cpufreq_generic_init(policy, freq_table, TRANSITION_LATENCY);
+       if (ret)
+               bmips_cpufreq_exit(policy);
+       else
+               pr_info("%s: registered\n", BMIPS_CPUFREQ_NAME);
+
+       return ret;
+}
+
+static struct cpufreq_driver bmips_cpufreq_driver = {
+       .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+       .verify         = cpufreq_generic_frequency_table_verify,
+       .target_index   = bmips_cpufreq_target_index,
+       .get            = bmips_cpufreq_get,
+       .init           = bmips_cpufreq_init,
+       .exit           = bmips_cpufreq_exit,
+       .attr           = cpufreq_generic_attr,
+       .name           = BMIPS_CPUFREQ_PREFIX,
+};
+
+static int __init bmips_cpufreq_probe(void)
+{
+       struct cpufreq_compat *cc;
+       struct device_node *np;
+
+       for (cc = bmips_cpufreq_compat; cc->compatible; cc++) {
+               np = of_find_compatible_node(NULL, "cpu", cc->compatible);
+               if (np) {
+                       of_node_put(np);
+                       priv = cc;
+                       break;
+               }
+       }
+
+       /* We hit the guard element of the array. No compatible CPU found. */
+       if (!cc->compatible)
+               return -ENODEV;
+
+       return cpufreq_register_driver(&bmips_cpufreq_driver);
+}
+device_initcall(bmips_cpufreq_probe);
+
+MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
+MODULE_DESCRIPTION("CPUfreq driver for Broadcom BMIPS SoCs");
+MODULE_LICENSE("GPL");