[PATCH 1/3] cpufreq: Add Tegra186 cpufreq driver

[Mikko Perttunen]

Add a new cpufreq driver for Tegra186 (and likely later).
The CPUs are organized into two clusters, Denver and A57,
with two and four cores respectively. CPU frequency can be
adjusted by writing the desired rate divisor and a voltage
hint to a special per-core register.

The frequency of each core can be set individually; however,
this is just a hint as all CPUs in a cluster will run at
the maximum rate of non-idle CPUs in the cluster.

Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx>
---
 drivers/cpufreq/Kconfig.arm        |   7 +
 drivers/cpufreq/Makefile           |   1 +
 drivers/cpufreq/tegra186-cpufreq.c | 277 +++++++++++++++++++++++++++++++++++++
 3 files changed, 285 insertions(+)
 create mode 100644 drivers/cpufreq/tegra186-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 74fa5c5904d3..168d36fa4a58 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -247,6 +247,13 @@ config ARM_TEGRA124_CPUFREQ
 	help
 	  This adds the CPUFreq driver support for Tegra124 SOCs.
 
+config ARM_TEGRA186_CPUFREQ
+	tristate "Tegra186 CPUFreq support"
+	depends on ARCH_TEGRA && TEGRA_BPMP
+	default y
+	help
+	  This adds the CPUFreq driver support for Tegra186 SOCs.
+
 config ARM_TI_CPUFREQ
 	bool "Texas Instruments CPUFreq support"
 	depends on ARCH_OMAP2PLUS
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 9f5a8045f36d..b7e78f063c4f 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -77,6 +77,7 @@ obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
 obj-$(CONFIG_ARM_STI_CPUFREQ)		+= sti-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o
+obj-$(CONFIG_ARM_TEGRA186_CPUFREQ)	+= tegra186-cpufreq.o
 obj-$(CONFIG_ARM_TI_CPUFREQ)		+= ti-cpufreq.o
 obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
 obj-$(CONFIG_ACPI_CPPC_CPUFREQ) += cppc_cpufreq.o
diff --git a/drivers/cpufreq/tegra186-cpufreq.c b/drivers/cpufreq/tegra186-cpufreq.c
new file mode 100644
index 000000000000..794c1f2d8231
--- /dev/null
+++ b/drivers/cpufreq/tegra186-cpufreq.c
@@ -0,0 +1,277 @@
+/*
+ * Copyright (c) 2017, NVIDIA CORPORATION. All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; 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/dma-mapping.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include <soc/tegra/bpmp.h>
+#include <soc/tegra/bpmp-abi.h>
+
+#define EDVD_CORE_VOLT_FREQ(core)		(0x20 + (core) * 0x4)
+#define EDVD_CORE_VOLT_FREQ_F_SHIFT		0
+#define EDVD_CORE_VOLT_FREQ_F_MASK		0xff
+#define EDVD_CORE_VOLT_FREQ_V_SHIFT		16
+#define EDVD_CORE_VOLT_FREQ_V_MASK		0xff
+
+#define CLUSTER_DENVER				0
+#define CLUSTER_A57				1
+#define NUM_CLUSTERS				2
+
+struct tegra186_cpufreq_cluster {
+	const char *name;
+	unsigned int num_cores;
+};
+
+static const struct tegra186_cpufreq_cluster CLUSTERS[] = {
+	{
+		.name = "denver",
+		.num_cores = 2,
+	},
+	{
+		.name = "a57",
+		.num_cores = 4,
+	}
+};
+
+struct tegra186_cpufreq_data {
+	void __iomem *regs[NUM_CLUSTERS];
+	struct cpufreq_frequency_table *tables[NUM_CLUSTERS];
+};
+
+static void get_cluster_core(int cpu, int *cluster, int *core)
+{
+	switch (cpu) {
+	case 0:
+		*cluster = CLUSTER_A57; *core = 0; break;
+	case 3:
+		*cluster = CLUSTER_A57; *core = 1; break;
+	case 4:
+		*cluster = CLUSTER_A57; *core = 2; break;
+	case 5:
+		*cluster = CLUSTER_A57; *core = 3; break;
+	case 1:
+		*cluster = CLUSTER_DENVER; *core = 0; break;
+	case 2:
+		*cluster = CLUSTER_DENVER; *core = 1; break;
+	}
+}
+
+static int tegra186_cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct tegra186_cpufreq_data *data = cpufreq_get_driver_data();
+	struct cpufreq_frequency_table *table;
+	int cluster, core;
+
+	get_cluster_core(policy->cpu, &cluster, &core);
+
+	table = data->tables[cluster];
+	cpufreq_table_validate_and_show(policy, table);
+
+	policy->cpuinfo.transition_latency = 300 * 1000;
+
+	return 0;
+}
+
+static void write_volt_freq(uint8_t vidx, uint8_t ndiv, void __iomem *regs,
+			unsigned int core)
+{
+	u32 val = 0;
+
+	val |= ndiv << EDVD_CORE_VOLT_FREQ_F_SHIFT;
+	val |= vidx << EDVD_CORE_VOLT_FREQ_V_SHIFT;
+
+	writel(val, regs + EDVD_CORE_VOLT_FREQ(core));
+}
+
+static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy,
+				       unsigned int index)
+{
+	struct cpufreq_frequency_table *tbl = policy->freq_table + index;
+	struct tegra186_cpufreq_data *data = cpufreq_get_driver_data();
+	uint16_t vidx = tbl->driver_data >> 16;
+	uint16_t ndiv = tbl->driver_data & 0xffff;
+	int cluster, core;
+
+	get_cluster_core(policy->cpu, &cluster, &core);
+	write_volt_freq(vidx, ndiv, data->regs[cluster], core);
+
+	return 0;
+}
+
+static struct cpufreq_driver tegra186_cpufreq_driver = {
+	.name = "tegra186",
+	.flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
+	.verify = cpufreq_generic_frequency_table_verify,
+	.target_index = tegra186_cpufreq_set_target,
+	.init = tegra186_cpufreq_init,
+	.attr = cpufreq_generic_attr,
+};
+
+static int init_vhint_table(struct platform_device *pdev,
+			    struct tegra_bpmp *bpmp, uint32_t cluster_id,
+			    struct cpufreq_frequency_table **table)
+{
+	struct mrq_cpu_vhint_request req;
+	struct tegra_bpmp_message msg;
+	struct cpu_vhint_data *data;
+	int err, i, j, num_rates;
+	dma_addr_t phys;
+	void *virt;
+
+	virt = dma_alloc_coherent(bpmp->dev, MSG_DATA_MIN_SZ, &phys,
+				  GFP_KERNEL | GFP_DMA32);
+	if (!virt)
+		return -ENOMEM;
+
+	data = (struct cpu_vhint_data *)virt;
+
+	memset(&req, 0, sizeof(req));
+	req.addr = phys;
+	req.cluster_id = cluster_id;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.mrq = MRQ_CPU_VHINT;
+	msg.tx.data = &req;
+	msg.tx.size = sizeof(req);
+
+	err = tegra_bpmp_transfer(bpmp, &msg);
+	if (err)
+		goto end;
+
+	num_rates = 0;
+
+	for (i = data->vfloor; i < data->vceil + 1; ++i) {
+		uint16_t ndiv = data->ndiv[i];
+
+		if (ndiv < data->ndiv_min || ndiv > data->ndiv_max)
+			continue;
+
+		/* Only store lowest voltage index for each rate */
+		if (i > 0 && ndiv == data->ndiv[i-1])
+			continue;
+
+		++num_rates;
+	}
+
+	*table = devm_kcalloc(&pdev->dev, num_rates + 1, sizeof(**table),
+			      GFP_KERNEL);
+	if (!*table) {
+		err = -ENOMEM;
+		goto end;
+	}
+
+	for (i = data->vfloor, j = 0; i < data->vceil + 1; ++i) {
+		struct cpufreq_frequency_table *point;
+		uint16_t ndiv = data->ndiv[i];
+
+		if (ndiv < data->ndiv_min || ndiv > data->ndiv_max)
+			continue;
+
+		/* Only store lowest voltage index for each rate */
+		if (i > 0 && ndiv == data->ndiv[i-1])
+			continue;
+
+		point = &(*table)[j++];
+		point->driver_data = (i << 16) | (ndiv);
+		point->frequency = data->ref_clk_hz * ndiv / data->pdiv /
+			data->mdiv / 1000;
+	}
+
+	(*table)[j].frequency = CPUFREQ_TABLE_END;
+
+end:
+	dma_free_coherent(bpmp->dev, MSG_DATA_MIN_SZ, virt, phys);
+
+	return err;
+}
+
+static int tegra186_cpufreq_probe(struct platform_device *pdev)
+{
+	struct tegra186_cpufreq_data *data;
+	struct tegra_bpmp *bpmp;
+	int i, err;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	bpmp = tegra_bpmp_get(&pdev->dev);
+	if (IS_ERR(bpmp))
+		return PTR_ERR(bpmp);
+
+	for (i = 0; i < NUM_CLUSTERS; ++i) {
+		struct resource *res;
+
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+						   CLUSTERS[i].name);
+		if (!res) {
+			err = -ENXIO;
+			goto put_bpmp;
+		}
+
+		data->regs[i] = devm_ioremap_resource(&pdev->dev, res);
+		if (IS_ERR(data->regs[i])) {
+			err = PTR_ERR(data->regs[i]);
+			goto put_bpmp;
+		}
+
+		err = init_vhint_table(pdev, bpmp, i, &data->tables[i]);
+		if (err)
+			goto put_bpmp;
+	}
+
+	tegra_bpmp_put(bpmp);
+
+	tegra186_cpufreq_driver.driver_data = data;
+
+	err = cpufreq_register_driver(&tegra186_cpufreq_driver);
+	if (err)
+		return err;
+
+	return 0;
+
+put_bpmp:
+	tegra_bpmp_put(bpmp);
+
+	return err;
+}
+
+static int tegra186_cpufreq_remove(struct platform_device *pdev)
+{
+	cpufreq_unregister_driver(&tegra186_cpufreq_driver);
+
+	return 0;
+}
+
+static const struct of_device_id tegra186_cpufreq_of_match[] = {
+	{ .compatible = "nvidia,tegra186-ccplex-cluster", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tegra186_cpufreq_of_match);
+
+static struct platform_driver tegra186_cpufreq_platform_driver = {
+	.driver = {
+		.name = "tegra186-cpufreq",
+		.of_match_table = tegra186_cpufreq_of_match,
+	},
+	.probe = tegra186_cpufreq_probe,
+	.remove = tegra186_cpufreq_remove,
+};
+module_platform_driver(tegra186_cpufreq_platform_driver);
+
+MODULE_AUTHOR("Mikko Perttunen <mperttunen@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Tegra186 cpufreq driver");
+MODULE_LICENSE("GPL v2");
-- 
2.1.4