[PATCH v2 3/4] cpufreq: bmips-cpufreq: CPUfreq driver for Broadcom's BMIPS SoCs

Markus Mayer
2017-02-06T21:52:16Z

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

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
---
drivers/cpufreq/Kconfig | 10 +++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/bmips-cpufreq.c | 195 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 206 insertions(+)
create mode 100644 drivers/cpufreq/bmips-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 15adef4..ec040a5 100644
--- 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 1e46c39..b7b3fc7 100644
--- 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
index 0000000..505aa83
--- /dev/null
+++ b/drivers/cpufreq/bmips-cpufreq.c
@@ -0,0 +1,195 @@
+/*
+ * 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 long freq, cpu_freq;
+ 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;
+ }
+
+ cpu_freq = htp_freq_to_cpu_freq(priv->clk_mult);
+ freq = cpu_freq / (1 << div);
+
+ return freq;
+}
+
+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;
+
+ /* Store the compatibility data. */
+ priv = cpufreq_get_driver_data();
+
+ 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);
+ bmips_cpufreq_driver.driver_data = 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");
--
2.7.4