[PATCH v2 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>
---
v2:
- Many cosmetic / restructuring changes
- Only one aperture read from DT now, with a new
  structure containing the offset among other details
  per cluster.
- Don't enable the driver by default.

 drivers/cpufreq/Kconfig.arm        |   6 +
 drivers/cpufreq/Makefile           |   1 +
 drivers/cpufreq/tegra186-cpufreq.c | 275 +++++++++++++++++++++++++++++++++++++
 3 files changed, 282 insertions(+)
 create mode 100644 drivers/cpufreq/tegra186-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 74fa5c5904d3..74ed7e9a7f27 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -247,6 +247,12 @@ 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
+	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..3c49591fa0ff
--- /dev/null
+++ b/drivers/cpufreq/tegra186-cpufreq.c
@@ -0,0 +1,275 @@
+/*
+ * 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_V_SHIFT		16
+
+struct tegra186_cpufreq_cluster_info {
+	unsigned long offset;
+	int cpus[4];
+	unsigned int bpmp_cluster_id;
+};
+
+#define NO_CPU -1
+static const struct tegra186_cpufreq_cluster_info tegra186_clusters[] = {
+	/* Denver cluster */
+	{
+		.offset = SZ_64K * 7,
+		.cpus = { 1, 2, NO_CPU, NO_CPU },
+		.bpmp_cluster_id = 0,
+	},
+	/* A57 cluster */
+	{
+		.offset = SZ_64K * 6,
+		.cpus = { 0, 3, 4, 5 },
+		.bpmp_cluster_id = 1,
+	},
+};
+
+struct tegra186_cpufreq_cluster {
+	const struct tegra186_cpufreq_cluster_info *info;
+	struct cpufreq_frequency_table *table;
+};
+
+struct tegra186_cpufreq_data {
+	void __iomem *regs;
+
+	size_t num_clusters;
+	struct tegra186_cpufreq_cluster *clusters;
+};
+
+static int tegra186_cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct tegra186_cpufreq_data *data = cpufreq_get_driver_data();
+	unsigned int i;
+
+	for (i = 0; i < data->num_clusters; i++) {
+		struct tegra186_cpufreq_cluster *cluster = &data->clusters[i];
+		const struct tegra186_cpufreq_cluster_info *info =
+			cluster->info;
+		int core;
+
+		for (core = 0; core < ARRAY_SIZE(info->cpus); core++) {
+			if (info->cpus[core] == policy->cpu)
+				break;
+		}
+		if (core == ARRAY_SIZE(info->cpus))
+			continue;
+
+		policy->driver_data =
+			data->regs + info->offset + EDVD_CORE_VOLT_FREQ(core);
+		cpufreq_table_validate_and_show(policy, cluster->table);
+	}
+
+	policy->cpuinfo.transition_latency = 300 * 1000;
+
+	return 0;
+}
+
+static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy,
+				       unsigned int index)
+{
+	struct cpufreq_frequency_table *tbl = policy->freq_table + index;
+	void __iomem *edvd_reg = policy->driver_data;
+	u32 edvd_val = tbl->driver_data;
+
+	writel(edvd_val, edvd_reg);
+
+	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 struct cpufreq_frequency_table *init_vhint_table(
+	struct platform_device *pdev, struct tegra_bpmp *bpmp,
+	unsigned int 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 = 0;
+	dma_addr_t phys;
+	void *virt;
+
+	virt = dma_alloc_coherent(bpmp->dev, sizeof(*data), &phys,
+				  GFP_KERNEL | GFP_DMA32);
+	if (!virt)
+		return ERR_PTR(-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) {
+		table = ERR_PTR(err);
+		goto free;
+	}
+
+	for (i = data->vfloor; i <= data->vceil; i++) {
+		u16 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) {
+		table = ERR_PTR(-ENOMEM);
+		goto free;
+	}
+
+	for (i = data->vfloor, j = 0; i <= data->vceil; i++) {
+		struct cpufreq_frequency_table *point;
+		u16 ndiv = data->ndiv[i];
+		u32 edvd_val = 0;
+
+		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;
+
+		edvd_val |= i << EDVD_CORE_VOLT_FREQ_V_SHIFT;
+		edvd_val |= ndiv << EDVD_CORE_VOLT_FREQ_F_SHIFT;
+
+		point = &table[j++];
+		point->driver_data = edvd_val;
+		point->frequency = data->ref_clk_hz * ndiv / data->pdiv /
+			data->mdiv / 1000;
+	}
+
+	table[j].frequency = CPUFREQ_TABLE_END;
+
+free:
+	dma_free_coherent(bpmp->dev, MSG_DATA_MIN_SZ, virt, phys);
+
+	return table;
+}
+
+static int tegra186_cpufreq_probe(struct platform_device *pdev)
+{
+	struct tegra186_cpufreq_data *data;
+	struct tegra_bpmp *bpmp;
+	struct resource *res;
+	unsigned int i = 0, err;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->clusters = devm_kcalloc(&pdev->dev, ARRAY_SIZE(tegra186_clusters),
+				      sizeof(*data->clusters), GFP_KERNEL);
+	if (!data->clusters)
+		return -ENOMEM;
+
+	data->num_clusters = ARRAY_SIZE(tegra186_clusters);
+
+	bpmp = tegra_bpmp_get(&pdev->dev);
+	if (IS_ERR(bpmp))
+		return PTR_ERR(bpmp);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	data->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->regs)) {
+		err = PTR_ERR(data->regs);
+		goto put_bpmp;
+	}
+
+	for (i = 0; i < data->num_clusters; i++) {
+		struct tegra186_cpufreq_cluster *cluster = &data->clusters[i];
+
+		cluster->info = &tegra186_clusters[i];
+		cluster->table = init_vhint_table(
+			pdev, bpmp, cluster->info->bpmp_cluster_id);
+		if (IS_ERR(cluster->table)) {
+			err = PTR_ERR(cluster->table);
+			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("NVIDIA Tegra186 cpufreq driver");
+MODULE_LICENSE("GPL v2");
-- 
2.1.4