1 files changed, 607 insertions, 0 deletions
diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
new file mode 100644
index 000000000..4596c3e32
--- /dev/null
+++ b/drivers/cpufreq/tegra194-cpufreq.c
@@ -0,0 +1,607 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020 - 2022, NVIDIA CORPORATION. All rights reserved
+ */
+
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <asm/smp_plat.h>
+
+#include <soc/tegra/bpmp.h>
+#include <soc/tegra/bpmp-abi.h>
+
+#define KHZ                     1000
+#define REF_CLK_MHZ             408 /* 408 MHz */
+#define US_DELAY                500
+#define CPUFREQ_TBL_STEP_HZ     (50 * KHZ * KHZ)
+#define MAX_CNT                 ~0U
+
+#define NDIV_MASK              0x1FF
+
+#define CORE_OFFSET(cpu)			(cpu * 8)
+#define CMU_CLKS_BASE				0x2000
+#define SCRATCH_FREQ_CORE_REG(data, cpu)	(data->regs + CMU_CLKS_BASE + CORE_OFFSET(cpu))
+
+#define MMCRAB_CLUSTER_BASE(cl)			(0x30000 + (cl * 0x10000))
+#define CLUSTER_ACTMON_BASE(data, cl) \
+			(data->regs + (MMCRAB_CLUSTER_BASE(cl) + data->soc->actmon_cntr_base))
+#define CORE_ACTMON_CNTR_REG(data, cl, cpu)	(CLUSTER_ACTMON_BASE(data, cl) + CORE_OFFSET(cpu))
+
+/* cpufreq transisition latency */
+#define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */
+
+struct tegra_cpu_ctr {
+	u32 cpu;
+	u32 coreclk_cnt, last_coreclk_cnt;
+	u32 refclk_cnt, last_refclk_cnt;
+};
+
+struct read_counters_work {
+	struct work_struct work;
+	struct tegra_cpu_ctr c;
+};
+
+struct tegra_cpufreq_ops {
+	void (*read_counters)(struct tegra_cpu_ctr *c);
+	void (*set_cpu_ndiv)(struct cpufreq_policy *policy, u64 ndiv);
+	void (*get_cpu_cluster_id)(u32 cpu, u32 *cpuid, u32 *clusterid);
+	int (*get_cpu_ndiv)(u32 cpu, u32 cpuid, u32 clusterid, u64 *ndiv);
+};
+
+struct tegra_cpufreq_soc {
+	struct tegra_cpufreq_ops *ops;
+	int maxcpus_per_cluster;
+	unsigned int num_clusters;
+	phys_addr_t actmon_cntr_base;
+};
+
+struct tegra194_cpufreq_data {
+	void __iomem *regs;
+	struct cpufreq_frequency_table **tables;
+	const struct tegra_cpufreq_soc *soc;
+};
+
+static struct workqueue_struct *read_counters_wq;
+
+static void tegra_get_cpu_mpidr(void *mpidr)
+{
+	*((u64 *)mpidr) = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
+}
+
+static void tegra234_get_cpu_cluster_id(u32 cpu, u32 *cpuid, u32 *clusterid)
+{
+	u64 mpidr;
+
+	smp_call_function_single(cpu, tegra_get_cpu_mpidr, &mpidr, true);
+
+	if (cpuid)
+		*cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+	if (clusterid)
+		*clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 2);
+}
+
+static int tegra234_get_cpu_ndiv(u32 cpu, u32 cpuid, u32 clusterid, u64 *ndiv)
+{
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	void __iomem *freq_core_reg;
+	u64 mpidr_id;
+
+	/* use physical id to get address of per core frequency register */
+	mpidr_id = (clusterid * data->soc->maxcpus_per_cluster) + cpuid;
+	freq_core_reg = SCRATCH_FREQ_CORE_REG(data, mpidr_id);
+
+	*ndiv = readl(freq_core_reg) & NDIV_MASK;
+
+	return 0;
+}
+
+static void tegra234_set_cpu_ndiv(struct cpufreq_policy *policy, u64 ndiv)
+{
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	void __iomem *freq_core_reg;
+	u32 cpu, cpuid, clusterid;
+	u64 mpidr_id;
+
+	for_each_cpu_and(cpu, policy->cpus, cpu_online_mask) {
+		data->soc->ops->get_cpu_cluster_id(cpu, &cpuid, &clusterid);
+
+		/* use physical id to get address of per core frequency register */
+		mpidr_id = (clusterid * data->soc->maxcpus_per_cluster) + cpuid;
+		freq_core_reg = SCRATCH_FREQ_CORE_REG(data, mpidr_id);
+
+		writel(ndiv, freq_core_reg);
+	}
+}
+
+/*
+ * This register provides access to two counter values with a single
+ * 64-bit read. The counter values are used to determine the average
+ * actual frequency a core has run at over a period of time.
+ *     [63:32] PLLP counter: Counts at fixed frequency (408 MHz)
+ *     [31:0] Core clock counter: Counts on every core clock cycle
+ */
+static void tegra234_read_counters(struct tegra_cpu_ctr *c)
+{
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	void __iomem *actmon_reg;
+	u32 cpuid, clusterid;
+	u64 val;
+
+	data->soc->ops->get_cpu_cluster_id(c->cpu, &cpuid, &clusterid);
+	actmon_reg = CORE_ACTMON_CNTR_REG(data, clusterid, cpuid);
+
+	val = readq(actmon_reg);
+	c->last_refclk_cnt = upper_32_bits(val);
+	c->last_coreclk_cnt = lower_32_bits(val);
+	udelay(US_DELAY);
+	val = readq(actmon_reg);
+	c->refclk_cnt = upper_32_bits(val);
+	c->coreclk_cnt = lower_32_bits(val);
+}
+
+static struct tegra_cpufreq_ops tegra234_cpufreq_ops = {
+	.read_counters = tegra234_read_counters,
+	.get_cpu_cluster_id = tegra234_get_cpu_cluster_id,
+	.get_cpu_ndiv = tegra234_get_cpu_ndiv,
+	.set_cpu_ndiv = tegra234_set_cpu_ndiv,
+};
+
+static const struct tegra_cpufreq_soc tegra234_cpufreq_soc = {
+	.ops = &tegra234_cpufreq_ops,
+	.actmon_cntr_base = 0x9000,
+	.maxcpus_per_cluster = 4,
+	.num_clusters = 3,
+};
+
+static const struct tegra_cpufreq_soc tegra239_cpufreq_soc = {
+	.ops = &tegra234_cpufreq_ops,
+	.actmon_cntr_base = 0x4000,
+	.maxcpus_per_cluster = 8,
+	.num_clusters = 1,
+};
+
+static void tegra194_get_cpu_cluster_id(u32 cpu, u32 *cpuid, u32 *clusterid)
+{
+	u64 mpidr;
+
+	smp_call_function_single(cpu, tegra_get_cpu_mpidr, &mpidr, true);
+
+	if (cpuid)
+		*cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+	if (clusterid)
+		*clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+}
+
+/*
+ * Read per-core Read-only system register NVFREQ_FEEDBACK_EL1.
+ * The register provides frequency feedback information to
+ * determine the average actual frequency a core has run at over
+ * a period of time.
+ *	[31:0] PLLP counter: Counts at fixed frequency (408 MHz)
+ *	[63:32] Core clock counter: counts on every core clock cycle
+ *			where the core is architecturally clocking
+ */
+static u64 read_freq_feedback(void)
+{
+	u64 val = 0;
+
+	asm volatile("mrs %0, s3_0_c15_c0_5" : "=r" (val) : );
+
+	return val;
+}
+
+static inline u32 map_ndiv_to_freq(struct mrq_cpu_ndiv_limits_response
+				   *nltbl, u16 ndiv)
+{
+	return nltbl->ref_clk_hz / KHZ * ndiv / (nltbl->pdiv * nltbl->mdiv);
+}
+
+static void tegra194_read_counters(struct tegra_cpu_ctr *c)
+{
+	u64 val;
+
+	val = read_freq_feedback();
+	c->last_refclk_cnt = lower_32_bits(val);
+	c->last_coreclk_cnt = upper_32_bits(val);
+	udelay(US_DELAY);
+	val = read_freq_feedback();
+	c->refclk_cnt = lower_32_bits(val);
+	c->coreclk_cnt = upper_32_bits(val);
+}
+
+static void tegra_read_counters(struct work_struct *work)
+{
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	struct read_counters_work *read_counters_work;
+	struct tegra_cpu_ctr *c;
+
+	/*
+	 * ref_clk_counter(32 bit counter) runs on constant clk,
+	 * pll_p(408MHz).
+	 * It will take = 2 ^ 32 / 408 MHz to overflow ref clk counter
+	 *              = 10526880 usec = 10.527 sec to overflow
+	 *
+	 * Like wise core_clk_counter(32 bit counter) runs on core clock.
+	 * It's synchronized to crab_clk (cpu_crab_clk) which runs at
+	 * freq of cluster. Assuming max cluster clock ~2000MHz,
+	 * It will take = 2 ^ 32 / 2000 MHz to overflow core clk counter
+	 *              = ~2.147 sec to overflow
+	 */
+	read_counters_work = container_of(work, struct read_counters_work,
+					  work);
+	c = &read_counters_work->c;
+
+	data->soc->ops->read_counters(c);
+}
+
+/*
+ * Return instantaneous cpu speed
+ * Instantaneous freq is calculated as -
+ * -Takes sample on every query of getting the freq.
+ *	- Read core and ref clock counters;
+ *	- Delay for X us
+ *	- Read above cycle counters again
+ *	- Calculates freq by subtracting current and previous counters
+ *	  divided by the delay time or eqv. of ref_clk_counter in delta time
+ *	- Return Kcycles/second, freq in KHz
+ *
+ *	delta time period = x sec
+ *			  = delta ref_clk_counter / (408 * 10^6) sec
+ *	freq in Hz = cycles/sec
+ *		   = (delta cycles / x sec
+ *		   = (delta cycles * 408 * 10^6) / delta ref_clk_counter
+ *	in KHz	   = (delta cycles * 408 * 10^3) / delta ref_clk_counter
+ *
+ * @cpu - logical cpu whose freq to be updated
+ * Returns freq in KHz on success, 0 if cpu is offline
+ */
+static unsigned int tegra194_calculate_speed(u32 cpu)
+{
+	struct read_counters_work read_counters_work;
+	struct tegra_cpu_ctr c;
+	u32 delta_refcnt;
+	u32 delta_ccnt;
+	u32 rate_mhz;
+
+	/*
+	 * udelay() is required to reconstruct cpu frequency over an
+	 * observation window. Using workqueue to call udelay() with
+	 * interrupts enabled.
+	 */
+	read_counters_work.c.cpu = cpu;
+	INIT_WORK_ONSTACK(&read_counters_work.work, tegra_read_counters);
+	queue_work_on(cpu, read_counters_wq, &read_counters_work.work);
+	flush_work(&read_counters_work.work);
+	c = read_counters_work.c;
+
+	if (c.coreclk_cnt < c.last_coreclk_cnt)
+		delta_ccnt = c.coreclk_cnt + (MAX_CNT - c.last_coreclk_cnt);
+	else
+		delta_ccnt = c.coreclk_cnt - c.last_coreclk_cnt;
+	if (!delta_ccnt)
+		return 0;
+
+	/* ref clock is 32 bits */
+	if (c.refclk_cnt < c.last_refclk_cnt)
+		delta_refcnt = c.refclk_cnt + (MAX_CNT - c.last_refclk_cnt);
+	else
+		delta_refcnt = c.refclk_cnt - c.last_refclk_cnt;
+	if (!delta_refcnt) {
+		pr_debug("cpufreq: %d is idle, delta_refcnt: 0\n", cpu);
+		return 0;
+	}
+	rate_mhz = ((unsigned long)(delta_ccnt * REF_CLK_MHZ)) / delta_refcnt;
+
+	return (rate_mhz * KHZ); /* in KHz */
+}
+
+static void tegra194_get_cpu_ndiv_sysreg(void *ndiv)
+{
+	u64 ndiv_val;
+
+	asm volatile("mrs %0, s3_0_c15_c0_4" : "=r" (ndiv_val) : );
+
+	*(u64 *)ndiv = ndiv_val;
+}
+
+static int tegra194_get_cpu_ndiv(u32 cpu, u32 cpuid, u32 clusterid, u64 *ndiv)
+{
+	return smp_call_function_single(cpu, tegra194_get_cpu_ndiv_sysreg, &ndiv, true);
+}
+
+static void tegra194_set_cpu_ndiv_sysreg(void *data)
+{
+	u64 ndiv_val = *(u64 *)data;
+
+	asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
+}
+
+static void tegra194_set_cpu_ndiv(struct cpufreq_policy *policy, u64 ndiv)
+{
+	on_each_cpu_mask(policy->cpus, tegra194_set_cpu_ndiv_sysreg, &ndiv, true);
+}
+
+static unsigned int tegra194_get_speed(u32 cpu)
+{
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	struct cpufreq_frequency_table *pos;
+	u32 cpuid, clusterid;
+	unsigned int rate;
+	u64 ndiv;
+	int ret;
+
+	data->soc->ops->get_cpu_cluster_id(cpu, &cpuid, &clusterid);
+
+	/* reconstruct actual cpu freq using counters */
+	rate = tegra194_calculate_speed(cpu);
+
+	/* get last written ndiv value */
+	ret = data->soc->ops->get_cpu_ndiv(cpu, cpuid, clusterid, &ndiv);
+	if (WARN_ON_ONCE(ret))
+		return rate;
+
+	/*
+	 * If the reconstructed frequency has acceptable delta from
+	 * the last written value, then return freq corresponding
+	 * to the last written ndiv value from freq_table. This is
+	 * done to return consistent value.
+	 */
+	cpufreq_for_each_valid_entry(pos, data->tables[clusterid]) {
+		if (pos->driver_data != ndiv)
+			continue;
+
+		if (abs(pos->frequency - rate) > 115200) {
+			pr_warn("cpufreq: cpu%d,cur:%u,set:%u,set ndiv:%llu\n",
+				cpu, rate, pos->frequency, ndiv);
+		} else {
+			rate = pos->frequency;
+		}
+		break;
+	}
+	return rate;
+}
+
+static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	int maxcpus_per_cluster = data->soc->maxcpus_per_cluster;
+	u32 start_cpu, cpu;
+	u32 clusterid;
+
+	data->soc->ops->get_cpu_cluster_id(policy->cpu, NULL, &clusterid);
+
+	if (clusterid >= data->soc->num_clusters || !data->tables[clusterid])
+		return -EINVAL;
+
+	start_cpu = rounddown(policy->cpu, maxcpus_per_cluster);
+	/* set same policy for all cpus in a cluster */
+	for (cpu = start_cpu; cpu < (start_cpu + maxcpus_per_cluster); cpu++) {
+		if (cpu_possible(cpu))
+			cpumask_set_cpu(cpu, policy->cpus);
+	}
+	policy->freq_table = data->tables[clusterid];
+	policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;
+
+	return 0;
+}
+
+static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
+				       unsigned int index)
+{
+	struct cpufreq_frequency_table *tbl = policy->freq_table + index;
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+
+	/*
+	 * Each core writes frequency in per core register. Then both cores
+	 * in a cluster run at same frequency which is the maximum frequency
+	 * request out of the values requested by both cores in that cluster.
+	 */
+	data->soc->ops->set_cpu_ndiv(policy, (u64)tbl->driver_data);
+
+	return 0;
+}
+
+static struct cpufreq_driver tegra194_cpufreq_driver = {
+	.name = "tegra194",
+	.flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify = cpufreq_generic_frequency_table_verify,
+	.target_index = tegra194_cpufreq_set_target,
+	.get = tegra194_get_speed,
+	.init = tegra194_cpufreq_init,
+	.attr = cpufreq_generic_attr,
+};
+
+static struct tegra_cpufreq_ops tegra194_cpufreq_ops = {
+	.read_counters = tegra194_read_counters,
+	.get_cpu_cluster_id = tegra194_get_cpu_cluster_id,
+	.get_cpu_ndiv = tegra194_get_cpu_ndiv,
+	.set_cpu_ndiv = tegra194_set_cpu_ndiv,
+};
+
+static const struct tegra_cpufreq_soc tegra194_cpufreq_soc = {
+	.ops = &tegra194_cpufreq_ops,
+	.maxcpus_per_cluster = 2,
+	.num_clusters = 4,
+};
+
+static void tegra194_cpufreq_free_resources(void)
+{
+	destroy_workqueue(read_counters_wq);
+}
+
+static struct cpufreq_frequency_table *
+init_freq_table(struct platform_device *pdev, struct tegra_bpmp *bpmp,
+		unsigned int cluster_id)
+{
+	struct cpufreq_frequency_table *freq_table;
+	struct mrq_cpu_ndiv_limits_response resp;
+	unsigned int num_freqs, ndiv, delta_ndiv;
+	struct mrq_cpu_ndiv_limits_request req;
+	struct tegra_bpmp_message msg;
+	u16 freq_table_step_size;
+	int err, index;
+
+	memset(&req, 0, sizeof(req));
+	req.cluster_id = cluster_id;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.mrq = MRQ_CPU_NDIV_LIMITS;
+	msg.tx.data = &req;
+	msg.tx.size = sizeof(req);
+	msg.rx.data = &resp;
+	msg.rx.size = sizeof(resp);
+
+	err = tegra_bpmp_transfer(bpmp, &msg);
+	if (err)
+		return ERR_PTR(err);
+	if (msg.rx.ret == -BPMP_EINVAL) {
+		/* Cluster not available */
+		return NULL;
+	}
+	if (msg.rx.ret)
+		return ERR_PTR(-EINVAL);
+
+	/*
+	 * Make sure frequency table step is a multiple of mdiv to match
+	 * vhint table granularity.
+	 */
+	freq_table_step_size = resp.mdiv *
+			DIV_ROUND_UP(CPUFREQ_TBL_STEP_HZ, resp.ref_clk_hz);
+
+	dev_dbg(&pdev->dev, "cluster %d: frequency table step size: %d\n",
+		cluster_id, freq_table_step_size);
+
+	delta_ndiv = resp.ndiv_max - resp.ndiv_min;
+
+	if (unlikely(delta_ndiv == 0)) {
+		num_freqs = 1;
+	} else {
+		/* We store both ndiv_min and ndiv_max hence the +1 */
+		num_freqs = delta_ndiv / freq_table_step_size + 1;
+	}
+
+	num_freqs += (delta_ndiv % freq_table_step_size) ? 1 : 0;
+
+	freq_table = devm_kcalloc(&pdev->dev, num_freqs + 1,
+				  sizeof(*freq_table), GFP_KERNEL);
+	if (!freq_table)
+		return ERR_PTR(-ENOMEM);
+
+	for (index = 0, ndiv = resp.ndiv_min;
+			ndiv < resp.ndiv_max;
+			index++, ndiv += freq_table_step_size) {
+		freq_table[index].driver_data = ndiv;
+		freq_table[index].frequency = map_ndiv_to_freq(&resp, ndiv);
+	}
+
+	freq_table[index].driver_data = resp.ndiv_max;
+	freq_table[index++].frequency = map_ndiv_to_freq(&resp, resp.ndiv_max);
+	freq_table[index].frequency = CPUFREQ_TABLE_END;
+
+	return freq_table;
+}
+
+static int tegra194_cpufreq_probe(struct platform_device *pdev)
+{
+	const struct tegra_cpufreq_soc *soc;
+	struct tegra194_cpufreq_data *data;
+	struct tegra_bpmp *bpmp;
+	int err, i;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	soc = of_device_get_match_data(&pdev->dev);
+
+	if (soc->ops && soc->maxcpus_per_cluster && soc->num_clusters) {
+		data->soc = soc;
+	} else {
+		dev_err(&pdev->dev, "soc data missing\n");
+		return -EINVAL;
+	}
+
+	data->tables = devm_kcalloc(&pdev->dev, data->soc->num_clusters,
+				    sizeof(*data->tables), GFP_KERNEL);
+	if (!data->tables)
+		return -ENOMEM;
+
+	if (soc->actmon_cntr_base) {
+		/* mmio registers are used for frequency request and re-construction */
+		data->regs = devm_platform_ioremap_resource(pdev, 0);
+		if (IS_ERR(data->regs))
+			return PTR_ERR(data->regs);
+	}
+
+	platform_set_drvdata(pdev, data);
+
+	bpmp = tegra_bpmp_get(&pdev->dev);
+	if (IS_ERR(bpmp))
+		return PTR_ERR(bpmp);
+
+	read_counters_wq = alloc_workqueue("read_counters_wq", __WQ_LEGACY, 1);
+	if (!read_counters_wq) {
+		dev_err(&pdev->dev, "fail to create_workqueue\n");
+		err = -EINVAL;
+		goto put_bpmp;
+	}
+
+	for (i = 0; i < data->soc->num_clusters; i++) {
+		data->tables[i] = init_freq_table(pdev, bpmp, i);
+		if (IS_ERR(data->tables[i])) {
+			err = PTR_ERR(data->tables[i]);
+			goto err_free_res;
+		}
+	}
+
+	tegra194_cpufreq_driver.driver_data = data;
+
+	err = cpufreq_register_driver(&tegra194_cpufreq_driver);
+	if (!err)
+		goto put_bpmp;
+
+err_free_res:
+	tegra194_cpufreq_free_resources();
+put_bpmp:
+	tegra_bpmp_put(bpmp);
+	return err;
+}
+
+static int tegra194_cpufreq_remove(struct platform_device *pdev)
+{
+	cpufreq_unregister_driver(&tegra194_cpufreq_driver);
+	tegra194_cpufreq_free_resources();
+
+	return 0;
+}
+
+static const struct of_device_id tegra194_cpufreq_of_match[] = {
+	{ .compatible = "nvidia,tegra194-ccplex", .data = &tegra194_cpufreq_soc },
+	{ .compatible = "nvidia,tegra234-ccplex-cluster", .data = &tegra234_cpufreq_soc },
+	{ .compatible = "nvidia,tegra239-ccplex-cluster", .data = &tegra239_cpufreq_soc },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, tegra194_cpufreq_of_match);
+
+static struct platform_driver tegra194_ccplex_driver = {
+	.driver = {
+		.name = "tegra194-cpufreq",
+		.of_match_table = tegra194_cpufreq_of_match,
+	},
+	.probe = tegra194_cpufreq_probe,
+	.remove = tegra194_cpufreq_remove,
+};
+module_platform_driver(tegra194_ccplex_driver);
+
+MODULE_AUTHOR("Mikko Perttunen <mperttunen@nvidia.com>");
+MODULE_AUTHOR("Sumit Gupta <sumitg@nvidia.com>");
+MODULE_DESCRIPTION("NVIDIA Tegra194 cpufreq driver");
+MODULE_LICENSE("GPL v2");