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Subject[RESEND, PATCH v4 1/2] cpufreq: Add sun50i nvmem based CPU scaling driver
Date
For some SoCs, the CPU frequency subset and voltage value of each OPP
varies based on the silicon variant in use. The sun50i-cpufreq-nvmem
driver reads the efuse value from the SoC to provide the OPP framework
with required information.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
---
MAINTAINERS | 7 +
drivers/cpufreq/Kconfig.arm | 12 ++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/cpufreq-dt-platdev.c | 2 +
drivers/cpufreq/sun50i-cpufreq-nvmem.c | 226 +++++++++++++++++++++++++
5 files changed, 248 insertions(+)
create mode 100644 drivers/cpufreq/sun50i-cpufreq-nvmem.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 57f496cff999..c57f869af9d7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -668,6 +668,13 @@ S: Maintained
F: Documentation/i2c/busses/i2c-ali1563
F: drivers/i2c/busses/i2c-ali1563.c

+ALLWINNER CPUFREQ DRIVER
+M: Yangtao Li <tiny.windzz@gmail.com>
+L: linux-pm@vger.kernel.org
+S: Maintained
+F: Documentation/devicetree/bindings/opp/sun50i-nvmem-cpufreq.txt
+F: drivers/cpufreq/sun50i-cpufreq-nvmem.c
+
ALLWINNER SECURITY SYSTEM
M: Corentin Labbe <clabbe.montjoie@gmail.com>
L: linux-crypto@vger.kernel.org
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index f8129edc145e..5796ecf13d7f 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -19,6 +19,18 @@ config ACPI_CPPC_CPUFREQ

If in doubt, say N.

+config ARM_ALLWINNER_SUN50I_CPUFREQ_NVMEM
+ tristate "Allwinner nvmem based SUN50I CPUFreq driver"
+ depends on ARCH_SUNXI
+ depends on NVMEM_SUNXI_SID
+ select PM_OPP
+ help
+ This adds the nvmem based CPUFreq driver for Allwinner
+ h6 SoC.
+
+ To compile this driver as a module, choose M here: the
+ module will be called sun50i-cpufreq-nvmem.
+
config ARM_ARMADA_37XX_CPUFREQ
tristate "Armada 37xx CPUFreq support"
depends on ARCH_MVEBU && CPUFREQ_DT
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 689b26c6f949..a78b8da80383 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -78,6 +78,7 @@ obj-$(CONFIG_ARM_SCMI_CPUFREQ) += scmi-cpufreq.o
obj-$(CONFIG_ARM_SCPI_CPUFREQ) += scpi-cpufreq.o
obj-$(CONFIG_ARM_SPEAR_CPUFREQ) += spear-cpufreq.o
obj-$(CONFIG_ARM_STI_CPUFREQ) += sti-cpufreq.o
+obj-$(CONFIG_ARM_ALLWINNER_SUN50I_CPUFREQ_NVMEM) += sun50i-cpufreq-nvmem.o
obj-$(CONFIG_ARM_TANGO_CPUFREQ) += tango-cpufreq.o
obj-$(CONFIG_ARM_TEGRA20_CPUFREQ) += tegra20-cpufreq.o
obj-$(CONFIG_ARM_TEGRA124_CPUFREQ) += tegra124-cpufreq.o
diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
index 47729a22c159..50e7810f3a28 100644
--- a/drivers/cpufreq/cpufreq-dt-platdev.c
+++ b/drivers/cpufreq/cpufreq-dt-platdev.c
@@ -105,6 +105,8 @@ static const struct of_device_id whitelist[] __initconst = {
* platforms using "operating-points-v2" property.
*/
static const struct of_device_id blacklist[] __initconst = {
+ { .compatible = "allwinner,sun50i-h6", },
+
{ .compatible = "calxeda,highbank", },
{ .compatible = "calxeda,ecx-2000", },

diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
new file mode 100644
index 000000000000..eca32e443716
--- /dev/null
+++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Allwinner CPUFreq nvmem based driver
+ *
+ * The sun50i-cpufreq-nvmem driver reads the efuse value from the SoC to
+ * provide the OPP framework with required information.
+ *
+ * Copyright (C) 2019 Yangtao Li <tiny.windzz@gmail.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/slab.h>
+
+#define MAX_NAME_LEN 7
+
+#define NVMEM_MASK 0x7
+#define NVMEM_SHIFT 5
+
+static struct platform_device *cpufreq_dt_pdev, *sun50i_cpufreq_pdev;
+
+/**
+ * sun50i_cpufreq_get_efuse() - Parse and return efuse value present on SoC
+ * @versions: Set to the value parsed from efuse
+ *
+ * Returns 0 if success.
+ */
+static int sun50i_cpufreq_get_efuse(u32 *versions)
+{
+ struct nvmem_cell *speedbin_nvmem;
+ struct device_node *np;
+ struct device *cpu_dev;
+ u32 *speedbin, efuse_value;
+ size_t len;
+ int ret;
+
+ cpu_dev = get_cpu_device(0);
+ if (!cpu_dev)
+ return -ENODEV;
+
+ np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
+ if (!np)
+ return -ENOENT;
+
+ ret = of_device_is_compatible(np,
+ "allwinner,sun50i-h6-operating-points");
+ if (!ret) {
+ of_node_put(np);
+ return -ENOENT;
+ }
+
+ speedbin_nvmem = of_nvmem_cell_get(np, NULL);
+ of_node_put(np);
+ if (IS_ERR(speedbin_nvmem)) {
+ if (PTR_ERR(speedbin_nvmem) != -EPROBE_DEFER)
+ pr_err("Could not get nvmem cell: %ld\n",
+ PTR_ERR(speedbin_nvmem));
+ return PTR_ERR(speedbin_nvmem);
+ }
+
+ speedbin = nvmem_cell_read(speedbin_nvmem, &len);
+ nvmem_cell_put(speedbin_nvmem);
+ if (IS_ERR(speedbin))
+ return PTR_ERR(speedbin);
+
+ efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
+ switch (efuse_value) {
+ case 0b0001:
+ *versions = 1;
+ break;
+ case 0b0011:
+ *versions = 2;
+ break;
+ default:
+ /*
+ * For other situations, we treat it as bin0.
+ * This vf table can be run for any good cpu.
+ */
+ *versions = 0;
+ break;
+ }
+
+ kfree(speedbin);
+ return 0;
+};
+
+static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
+{
+ struct opp_table **opp_tables;
+ char name[MAX_NAME_LEN];
+ unsigned int cpu;
+ u32 speed = 0;
+ int ret;
+
+ opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
+ GFP_KERNEL);
+ if (!opp_tables)
+ return -ENOMEM;
+
+ ret = sun50i_cpufreq_get_efuse(&speed);
+ if (ret)
+ return ret;
+
+ snprintf(name, MAX_NAME_LEN, "speed%d", speed);
+
+ for_each_possible_cpu(cpu) {
+ struct device *cpu_dev = get_cpu_device(cpu);
+
+ if (!cpu_dev) {
+ ret = -ENODEV;
+ goto free_opp;
+ }
+
+ opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
+ if (IS_ERR(opp_tables[cpu])) {
+ ret = PTR_ERR(opp_tables[cpu]);
+ pr_err("Failed to set prop name\n");
+ goto free_opp;
+ }
+ }
+
+ cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
+ NULL, 0);
+ if (!IS_ERR(cpufreq_dt_pdev)) {
+ platform_set_drvdata(pdev, opp_tables);
+ return 0;
+ }
+
+ ret = PTR_ERR(cpufreq_dt_pdev);
+ pr_err("Failed to register platform device\n");
+
+free_opp:
+ for_each_possible_cpu(cpu) {
+ if (IS_ERR_OR_NULL(opp_tables[cpu]))
+ break;
+ dev_pm_opp_put_prop_name(opp_tables[cpu]);
+ }
+ kfree(opp_tables);
+
+ return ret;
+}
+
+static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
+{
+ struct opp_table **opp_tables = platform_get_drvdata(pdev);
+ unsigned int cpu;
+
+ platform_device_unregister(cpufreq_dt_pdev);
+
+ for_each_possible_cpu(cpu)
+ dev_pm_opp_put_prop_name(opp_tables[cpu]);
+
+ kfree(opp_tables);
+
+ return 0;
+}
+
+static struct platform_driver sun50i_cpufreq_driver = {
+ .probe = sun50i_cpufreq_nvmem_probe,
+ .remove = sun50i_cpufreq_nvmem_remove,
+ .driver = {
+ .name = "sun50i-cpufreq-nvmem",
+ },
+};
+
+static const struct of_device_id sun50i_cpufreq_match_list[] = {
+ { .compatible = "allwinner,sun50i-h6" },
+ {}
+};
+
+static const struct of_device_id *sun50i_cpufreq_match_node(void)
+{
+ const struct of_device_id *match;
+ struct device_node *np;
+
+ np = of_find_node_by_path("/");
+ match = of_match_node(sun50i_cpufreq_match_list, np);
+ of_node_put(np);
+
+ return match;
+}
+
+/*
+ * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
+ * all the real activity is done in the probe, which may be defered as well.
+ * The init here is only registering the driver and the platform device.
+ */
+static int __init sun50i_cpufreq_init(void)
+{
+ const struct of_device_id *match;
+ int ret;
+
+ match = sun50i_cpufreq_match_node();
+ if (!match)
+ return -ENODEV;
+
+ ret = platform_driver_register(&sun50i_cpufreq_driver);
+ if (unlikely(ret < 0))
+ return ret;
+
+ sun50i_cpufreq_pdev =
+ platform_device_register_simple("sun50i-cpufreq-nvmem",
+ -1, NULL, 0);
+ ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
+ if (ret == 0)
+ return 0;
+
+ platform_driver_unregister(&sun50i_cpufreq_driver);
+ return ret;
+}
+module_init(sun50i_cpufreq_init);
+
+static void __exit sun50i_cpufreq_exit(void)
+{
+ platform_device_unregister(sun50i_cpufreq_pdev);
+ platform_driver_unregister(&sun50i_cpufreq_driver);
+}
+module_exit(sun50i_cpufreq_exit);
+
+MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
+MODULE_LICENSE("GPL v2");
--
2.17.0
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