[TEGRA194_CPUFREQ PATCH v6 0/3] Add cpufreq driver for Tegra194

[TEGRA194_CPUFREQ PATCH v6 0/3] Add cpufreq driver for Tegra194

[Sumit Gupta]

Hi Viresh & Rob,

Have made the changes as per feedback.
Please review/ack and consider this patch set for merging in 5.9.

Thank you,
Sumit
---

The patch series adds cpufreq driver for Tegra194 SOC.

v5[5] -> v6
- Add new schema file for 'nvidia,tegra194-ccplex'[Rob].
- Minor changes suggested in cpufreq driver[Viresh].

v4[4] -> v5
- Don't call destroy_workqueue() if alloc_workqueue() fails[Viresh]
- Move CONFIG_ARM_TEGRA194_CPUFREQ enabling to soc/tegra/Kconfig[Viresh]
- Add dependency of 'nvidia,bpmp' on 'compatible' in yaml file[Michal]
- Fix typo in description causing dt_binding_check bot failure[Rob]

v3[3] -> v4
- Open code LOOP_FOR_EACH_CPU_OF_CLUSTER macro[Viresh]
- Delete unused funciton map_freq_to_ndiv[Viresh, kernel test bot]
- Remove flush_workqueue from free_resources[Viresh]

v2[2] -> v3
- Set same policy for all cpus in a cluster[Viresh].
- Add compatible string for CPU Complex under cpus node[Thierry].
- Add reference to bpmp node under cpus node[Thierry].
- Bind cpufreq driver to CPU Complex compatible string[Thierry].
- Remove patch to get bpmp data as now using cpus node to get that[Thierry].

v1[1] -> v2:
- Remove cpufreq_lock mutex from tegra194_cpufreq_set_target [Viresh].
- Remove CPUFREQ_ASYNC_NOTIFICATION flag [Viresh].
- Remove redundant _begin|end() call from tegra194_cpufreq_set_target.
- Rename opp_table to freq_table [Viresh].


Sumit Gupta (3):
  dt-bindings: arm: Add NVIDIA Tegra194 CPU Complex binding
  arm64: tegra: Add t194 ccplex compatible and bpmp property
  cpufreq: Add Tegra194 cpufreq driver

 .../bindings/arm/nvidia,tegra194-ccplex.yaml       |  69 ++++
 arch/arm64/boot/dts/nvidia/tegra194.dtsi           |   2 +
 drivers/cpufreq/Kconfig.arm                        |   7 +
 drivers/cpufreq/Makefile                           |   1 +
 drivers/cpufreq/tegra194-cpufreq.c                 | 397 +++++++++++++++++++++
 5 files changed, 476 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/nvidia,tegra194-ccplex.yaml
 create mode 100644 drivers/cpufreq/tegra194-cpufreq.c

[1] https://marc.info/?t=157539452300001&r=1&w=2
[2] https://marc.info/?l=linux-tegra&m=158602857106213&w=2
[3] https://marc.info/?l=linux-pm&m=159283376010084&w=2
[4] https://marc.info/?l=linux-tegra&m=159318640622917&w=2
[5] https://marc.info/?l=linux-tegra&m=159465409805593&w=2 
-- 
2.7.4

[TEGRA194_CPUFREQ PATCH v6 1/3] dt-bindings: arm: Add NVIDIA Tegra194 CPU Complex binding

[Sumit Gupta]

Add device-tree binding documentation to represent Tegra194
CPU Complex with compatible string under 'cpus' node. This
can be used by drivers like cpufreq which don't have their
node or CPU Complex node to bind to. Also, documenting
'nvidia,bpmp' property which points to BPMP device.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 .../bindings/arm/nvidia,tegra194-ccplex.yaml       | 69 ++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/nvidia,tegra194-ccplex.yaml

diff --git a/Documentation/devicetree/bindings/arm/nvidia,tegra194-ccplex.yaml b/Documentation/devicetree/bindings/arm/nvidia,tegra194-ccplex.yaml
new file mode 100644
index 0000000..1043e4b
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/nvidia,tegra194-ccplex.yaml
@@ -0,0 +1,69 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/arm/nvidia,tegra194-ccplex.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: NVIDIA Tegra194 CPU Complex device tree bindings
+
+maintainers:
+  - Thierry Reding <thierry.reding@gmail.com>
+  - Jonathan Hunter <jonathanh@nvidia.com>
+  - Sumit Gupta <sumitg@nvidia.com>
+
+description: |+
+  Tegra194 SOC has homogeneous architecture where each cluster has two
+  symmetric cores. Compatible string in "cpus" node represents the CPU
+  Complex having all clusters.
+
+properties:
+  $nodename:
+    const: cpus
+
+  compatible:
+    enum:
+      - nvidia,tegra194-ccplex
+
+  nvidia,bpmp:
+    $ref: '/schemas/types.yaml#/definitions/phandle'
+    description: |
+      Specifies the bpmp node that needs to be queried to get
+      operating point data for all CPUs.
+
+examples:
+  - |
+    cpus {
+      compatible = "nvidia,tegra194-ccplex";
+      nvidia,bpmp = <&bpmp>;
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      cpu0_0: cpu@0 {
+        compatible = "nvidia,tegra194-carmel";
+        device_type = "cpu";
+        reg = <0x0>;
+        enable-method = "psci";
+      };
+
+      cpu0_1: cpu@1 {
+        compatible = "nvidia,tegra194-carmel";
+        device_type = "cpu";
+        reg = <0x001>;
+        enable-method = "psci";
+      };
+
+      cpu1_0: cpu@100 {
+        compatible = "nvidia,tegra194-carmel";
+        device_type = "cpu";
+        reg = <0x100>;
+        enable-method = "psci";
+      };
+
+      cpu1_1: cpu@101 {
+        compatible = "nvidia,tegra194-carmel";
+        device_type = "cpu";
+        reg = <0x101>;
+        enable-method = "psci";
+      };
+    };
+...
-- 
2.7.4

Re: [TEGRA194_CPUFREQ PATCH v6 1/3] dt-bindings: arm: Add NVIDIA Tegra194 CPU Complex binding

[Rob Herring]

On Wed, 15 Jul 2020 19:01:23 +0530, Sumit Gupta wrote:
> Add device-tree binding documentation to represent Tegra194
> CPU Complex with compatible string under 'cpus' node. This
> can be used by drivers like cpufreq which don't have their
> node or CPU Complex node to bind to. Also, documenting
> 'nvidia,bpmp' property which points to BPMP device.
> 
> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> ---
>  .../bindings/arm/nvidia,tegra194-ccplex.yaml       | 69 ++++++++++++++++++++++
>  1 file changed, 69 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/nvidia,tegra194-ccplex.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>

[TEGRA194_CPUFREQ PATCH v6 2/3] arm64: tegra: Add t194 ccplex compatible and bpmp property

[Sumit Gupta]

On Tegra194, data on valid operating points for the CPUs needs to be
queried from BPMP. In T194, there is no node representing CPU complex.
So, add compatible string to the 'cpus' node instead of using dummy
node to bind cpufreq driver. Also, add reference to the BPMP instance
for the CPU complex.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 arch/arm64/boot/dts/nvidia/tegra194.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/nvidia/tegra194.dtsi b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
index 7c9511a..0abf287 100644
--- a/arch/arm64/boot/dts/nvidia/tegra194.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
@@ -1764,6 +1764,8 @@
 	};
 
 	cpus {
+		compatible = "nvidia,tegra194-ccplex";
+		nvidia,bpmp = <&bpmp>;
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-- 
2.7.4

Re: [TEGRA194_CPUFREQ PATCH v6 2/3] arm64: tegra: Add t194 ccplex compatible and bpmp property

[Thierry Reding]

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On Wed, Jul 15, 2020 at 07:01:24PM +0530, Sumit Gupta wrote:
> On Tegra194, data on valid operating points for the CPUs needs to be
> queried from BPMP. In T194, there is no node representing CPU complex.
> So, add compatible string to the 'cpus' node instead of using dummy
> node to bind cpufreq driver. Also, add reference to the BPMP instance
> for the CPU complex.
> 
> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> ---
>  arch/arm64/boot/dts/nvidia/tegra194.dtsi | 2 ++
>  1 file changed, 2 insertions(+)

Looks like the DT bindings are now done so I've applied this for v5.9.

Viresh, are you going to pick up the other patches, or do you want me
to pick them up and send you a pull request?

Thanks,
Thierry

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Re: [TEGRA194_CPUFREQ PATCH v6 2/3] arm64: tegra: Add t194 ccplex compatible and bpmp property

[Viresh Kumar]

On 16-07-20, 14:37, Thierry Reding wrote:
> On Wed, Jul 15, 2020 at 07:01:24PM +0530, Sumit Gupta wrote:
> > On Tegra194, data on valid operating points for the CPUs needs to be
> > queried from BPMP. In T194, there is no node representing CPU complex.
> > So, add compatible string to the 'cpus' node instead of using dummy
> > node to bind cpufreq driver. Also, add reference to the BPMP instance
> > for the CPU complex.
> > 
> > Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> > ---
> >  arch/arm64/boot/dts/nvidia/tegra194.dtsi | 2 ++
> >  1 file changed, 2 insertions(+)
> 
> Looks like the DT bindings are now done so I've applied this for v5.9.
> 
> Viresh, are you going to pick up the other patches, or do you want me
> to pick them up and send you a pull request?

Applied the other two patches, Thanks.

-- 
viresh

[TEGRA194_CPUFREQ PATCH v6 3/3] cpufreq: Add Tegra194 cpufreq driver

[Sumit Gupta]

Add support for CPU frequency scaling on Tegra194. The frequency
of each core can be adjusted by writing a clock divisor value to
a MSR on the core. The range of valid divisors is queried from
the BPMP.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 drivers/cpufreq/Kconfig.arm        |   7 +
 drivers/cpufreq/Makefile           |   1 +
 drivers/cpufreq/tegra194-cpufreq.c | 397 +++++++++++++++++++++++++++++++++++++
 3 files changed, 405 insertions(+)
 create mode 100644 drivers/cpufreq/tegra194-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 15c1a12..7e99a46 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -314,6 +314,13 @@ config ARM_TEGRA186_CPUFREQ
 	help
 	  This adds the CPUFreq driver support for Tegra186 SOCs.
 
+config ARM_TEGRA194_CPUFREQ
+	tristate "Tegra194 CPUFreq support"
+	depends on ARCH_TEGRA_194_SOC && TEGRA_BPMP
+	default y
+	help
+	  This adds CPU frequency driver support for Tegra194 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 f6670c4..66b5563 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_ARM_TANGO_CPUFREQ)		+= tango-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA186_CPUFREQ)	+= tegra186-cpufreq.o
+obj-$(CONFIG_ARM_TEGRA194_CPUFREQ)	+= tegra194-cpufreq.o
 obj-$(CONFIG_ARM_TI_CPUFREQ)		+= ti-cpufreq.o
 obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
 
diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
new file mode 100644
index 0000000..b52a5e2
--- /dev/null
+++ b/drivers/cpufreq/tegra194-cpufreq.c
@@ -0,0 +1,397 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020, 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 US_DELAY_MIN            2
+#define CPUFREQ_TBL_STEP_HZ     (50 * KHZ * KHZ)
+#define MAX_CNT                 ~0U
+
+/* cpufreq transisition latency */
+#define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */
+
+enum cluster {
+	CLUSTER0,
+	CLUSTER1,
+	CLUSTER2,
+	CLUSTER3,
+	MAX_CLUSTERS,
+};
+
+struct tegra194_cpufreq_data {
+	void __iomem *regs;
+	size_t num_clusters;
+	struct cpufreq_frequency_table **tables;
+};
+
+struct tegra_cpu_ctr {
+	u32 cpu;
+	u32 delay;
+	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;
+};
+
+static struct workqueue_struct *read_counters_wq;
+
+static enum cluster get_cpu_cluster(u8 cpu)
+{
+	return MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 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 tegra_read_counters(struct work_struct *work)
+{
+	struct read_counters_work *read_counters_work;
+	struct tegra_cpu_ctr *c;
+	u64 val;
+
+	/*
+	 * 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;
+
+	val = read_freq_feedback();
+	c->last_refclk_cnt = lower_32_bits(val);
+	c->last_coreclk_cnt = upper_32_bits(val);
+	udelay(c->delay);
+	val = read_freq_feedback();
+	c->refclk_cnt = lower_32_bits(val);
+	c->coreclk_cnt = upper_32_bits(val);
+}
+
+/*
+ * 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_get_speed_common(u32 cpu, u32 delay)
+{
+	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;
+	read_counters_work.c.delay = delay;
+	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 unsigned int tegra194_get_speed(u32 cpu)
+{
+	return tegra194_get_speed_common(cpu, US_DELAY);
+}
+
+static unsigned int tegra194_fast_get_speed(u32 cpu)
+{
+	return tegra194_get_speed_common(cpu, US_DELAY_MIN);
+}
+
+static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	int cl = get_cpu_cluster(policy->cpu);
+	u32 cpu;
+
+	if (cl >= data->num_clusters)
+		return -EINVAL;
+
+	policy->cur = tegra194_fast_get_speed(policy->cpu); /* boot freq */
+
+	/* set same policy for all cpus in a cluster */
+	for (cpu = (cl * 2); cpu < ((cl + 1) * 2); cpu++)
+		cpumask_set_cpu(cpu, policy->cpus);
+
+	policy->freq_table = data->tables[cl];
+	policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;
+
+	return 0;
+}
+
+static void set_cpu_ndiv(void *data)
+{
+	struct cpufreq_frequency_table *tbl = data;
+	u64 ndiv_val = (u64)tbl->driver_data;
+
+	asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
+}
+
+static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
+				       unsigned int index)
+{
+	struct cpufreq_frequency_table *tbl = policy->freq_table + index;
+
+	/*
+	 * 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.
+	 */
+	on_each_cpu_mask(policy->cpus, set_cpu_ndiv, tbl, true);
+
+	return 0;
+}
+
+static struct cpufreq_driver tegra194_cpufreq_driver = {
+	.name = "tegra194",
+	.flags = CPUFREQ_STICKY | 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 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);
+
+	/*
+	 * 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)
+{
+	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;
+
+	data->num_clusters = MAX_CLUSTERS;
+	data->tables = devm_kcalloc(&pdev->dev, data->num_clusters,
+				    sizeof(*data->tables), GFP_KERNEL);
+	if (!data->tables)
+		return -ENOMEM;
+
+	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->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 err_free_res;
+
+	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", },
+	{ /* 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");
-- 
2.7.4

Re: [TEGRA194_CPUFREQ PATCH v6 3/3] cpufreq: Add Tegra194 cpufreq driver

[Jon Hunter]

On 15/07/2020 14:31, Sumit Gupta wrote:
> Add support for CPU frequency scaling on Tegra194. The frequency
> of each core can be adjusted by writing a clock divisor value to
> a MSR on the core. The range of valid divisors is queried from
> the BPMP.
> 
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> ---
>  drivers/cpufreq/Kconfig.arm        |   7 +
>  drivers/cpufreq/Makefile           |   1 +
>  drivers/cpufreq/tegra194-cpufreq.c | 397 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 405 insertions(+)
>  create mode 100644 drivers/cpufreq/tegra194-cpufreq.c
> 
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 15c1a12..7e99a46 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -314,6 +314,13 @@ config ARM_TEGRA186_CPUFREQ
>  	help
>  	  This adds the CPUFreq driver support for Tegra186 SOCs.
>  
> +config ARM_TEGRA194_CPUFREQ
> +	tristate "Tegra194 CPUFreq support"
> +	depends on ARCH_TEGRA_194_SOC && TEGRA_BPMP
> +	default y
> +	help
> +	  This adds CPU frequency driver support for Tegra194 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 f6670c4..66b5563 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -83,6 +83,7 @@ obj-$(CONFIG_ARM_TANGO_CPUFREQ)		+= tango-cpufreq.o
>  obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o
>  obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o
>  obj-$(CONFIG_ARM_TEGRA186_CPUFREQ)	+= tegra186-cpufreq.o
> +obj-$(CONFIG_ARM_TEGRA194_CPUFREQ)	+= tegra194-cpufreq.o
>  obj-$(CONFIG_ARM_TI_CPUFREQ)		+= ti-cpufreq.o
>  obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
>  
> diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
> new file mode 100644
> index 0000000..b52a5e2
> --- /dev/null
> +++ b/drivers/cpufreq/tegra194-cpufreq.c
> @@ -0,0 +1,397 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2020, 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 US_DELAY_MIN            2
> +#define CPUFREQ_TBL_STEP_HZ     (50 * KHZ * KHZ)
> +#define MAX_CNT                 ~0U
> +
> +/* cpufreq transisition latency */
> +#define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */
> +
> +enum cluster {
> +	CLUSTER0,
> +	CLUSTER1,
> +	CLUSTER2,
> +	CLUSTER3,
> +	MAX_CLUSTERS,
> +};
> +
> +struct tegra194_cpufreq_data {
> +	void __iomem *regs;
> +	size_t num_clusters;
> +	struct cpufreq_frequency_table **tables;
> +};
> +
> +struct tegra_cpu_ctr {
> +	u32 cpu;
> +	u32 delay;
> +	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;
> +};
> +
> +static struct workqueue_struct *read_counters_wq;
> +
> +static enum cluster get_cpu_cluster(u8 cpu)
> +{
> +	return MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 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 tegra_read_counters(struct work_struct *work)
> +{
> +	struct read_counters_work *read_counters_work;
> +	struct tegra_cpu_ctr *c;
> +	u64 val;
> +
> +	/*
> +	 * 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;
> +
> +	val = read_freq_feedback();
> +	c->last_refclk_cnt = lower_32_bits(val);
> +	c->last_coreclk_cnt = upper_32_bits(val);
> +	udelay(c->delay);
> +	val = read_freq_feedback();
> +	c->refclk_cnt = lower_32_bits(val);
> +	c->coreclk_cnt = upper_32_bits(val);
> +}
> +
> +/*
> + * 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_get_speed_common(u32 cpu, u32 delay)
> +{
> +	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;
> +	read_counters_work.c.delay = delay;
> +	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 unsigned int tegra194_get_speed(u32 cpu)
> +{
> +	return tegra194_get_speed_common(cpu, US_DELAY);
> +}
> +
> +static unsigned int tegra194_fast_get_speed(u32 cpu)
> +{
> +	return tegra194_get_speed_common(cpu, US_DELAY_MIN);
> +}

Personally, I would not bother with the above function as it is only
used in one place.

> +
> +static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
> +{
> +	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
> +	int cl = get_cpu_cluster(policy->cpu);
> +	u32 cpu;
> +
> +	if (cl >= data->num_clusters)
> +		return -EINVAL;
> +
> +	policy->cur = tegra194_fast_get_speed(policy->cpu); /* boot freq */
> +
> +	/* set same policy for all cpus in a cluster */
> +	for (cpu = (cl * 2); cpu < ((cl + 1) * 2); cpu++)
> +		cpumask_set_cpu(cpu, policy->cpus);
> +
> +	policy->freq_table = data->tables[cl];
> +	policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;
> +
> +	return 0;
> +}
> +
> +static void set_cpu_ndiv(void *data)
> +{
> +	struct cpufreq_frequency_table *tbl = data;
> +	u64 ndiv_val = (u64)tbl->driver_data;
> +
> +	asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
> +}
> +
> +static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
> +				       unsigned int index)
> +{
> +	struct cpufreq_frequency_table *tbl = policy->freq_table + index;
> +
> +	/*
> +	 * 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.
> +	 */
> +	on_each_cpu_mask(policy->cpus, set_cpu_ndiv, tbl, true);
> +
> +	return 0;
> +}
> +
> +static struct cpufreq_driver tegra194_cpufreq_driver = {
> +	.name = "tegra194",
> +	.flags = CPUFREQ_STICKY | 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 void tegra194_cpufreq_free_resources(void)
> +{
> +	destroy_workqueue(read_counters_wq);
> +}

I would not bother with adding this function either.

> +
> +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);
> +
> +	/*
> +	 * 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)
> +{
> +	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;
> +
> +	data->num_clusters = MAX_CLUSTERS;
> +	data->tables = devm_kcalloc(&pdev->dev, data->num_clusters,
> +				    sizeof(*data->tables), GFP_KERNEL);
> +	if (!data->tables)
> +		return -ENOMEM;
> +
> +	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->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 err_free_res;

You don't need the above if statement now you added the below.

> +
> +	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", },
> +	{ /* 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");
> 

Cheers
Jon

-- 
nvpublic

Re: [TEGRA194_CPUFREQ PATCH v6 3/3] cpufreq: Add Tegra194 cpufreq driver

[Sumit Gupta]

>> Add support for CPU frequency scaling on Tegra194. The frequency
>> of each core can be adjusted by writing a clock divisor value to
>> a MSR on the core. The range of valid divisors is queried from
>> the BPMP.
>>
>> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
>> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
>> ---
>>   drivers/cpufreq/Kconfig.arm        |   7 +
>>   drivers/cpufreq/Makefile           |   1 +
>>   drivers/cpufreq/tegra194-cpufreq.c | 397 +++++++++++++++++++++++++++++++++++++
>>   3 files changed, 405 insertions(+)
>>   create mode 100644 drivers/cpufreq/tegra194-cpufreq.c
>>
>> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
>> index 15c1a12..7e99a46 100644
>> --- a/drivers/cpufreq/Kconfig.arm
>> +++ b/drivers/cpufreq/Kconfig.arm
>> @@ -314,6 +314,13 @@ config ARM_TEGRA186_CPUFREQ
>>   	help
>>   	  This adds the CPUFreq driver support for Tegra186 SOCs.
>>   
>> +config ARM_TEGRA194_CPUFREQ
>> +	tristate "Tegra194 CPUFreq support"
>> +	depends on ARCH_TEGRA_194_SOC && TEGRA_BPMP
>> +	default y
>> +	help
>> +	  This adds CPU frequency driver support for Tegra194 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 f6670c4..66b5563 100644
>> --- a/drivers/cpufreq/Makefile
>> +++ b/drivers/cpufreq/Makefile
>> @@ -83,6 +83,7 @@ obj-$(CONFIG_ARM_TANGO_CPUFREQ)		+= tango-cpufreq.o
>>   obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o
>>   obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o
>>   obj-$(CONFIG_ARM_TEGRA186_CPUFREQ)	+= tegra186-cpufreq.o
>> +obj-$(CONFIG_ARM_TEGRA194_CPUFREQ)	+= tegra194-cpufreq.o
>>   obj-$(CONFIG_ARM_TI_CPUFREQ)		+= ti-cpufreq.o
>>   obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
>>   
>> diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
>> new file mode 100644
>> index 0000000..b52a5e2
>> --- /dev/null
>> +++ b/drivers/cpufreq/tegra194-cpufreq.c
>> @@ -0,0 +1,397 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2020, 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 US_DELAY_MIN            2
>> +#define CPUFREQ_TBL_STEP_HZ     (50 * KHZ * KHZ)
>> +#define MAX_CNT                 ~0U
>> +
>> +/* cpufreq transisition latency */
>> +#define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */
>> +
>> +enum cluster {
>> +	CLUSTER0,
>> +	CLUSTER1,
>> +	CLUSTER2,
>> +	CLUSTER3,
>> +	MAX_CLUSTERS,
>> +};
>> +
>> +struct tegra194_cpufreq_data {
>> +	void __iomem *regs;
>> +	size_t num_clusters;
>> +	struct cpufreq_frequency_table **tables;
>> +};
>> +
>> +struct tegra_cpu_ctr {
>> +	u32 cpu;
>> +	u32 delay;
>> +	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;
>> +};
>> +
>> +static struct workqueue_struct *read_counters_wq;
>> +
>> +static enum cluster get_cpu_cluster(u8 cpu)
>> +{
>> +	return MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 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 tegra_read_counters(struct work_struct *work)
>> +{
>> +	struct read_counters_work *read_counters_work;
>> +	struct tegra_cpu_ctr *c;
>> +	u64 val;
>> +
>> +	/*
>> +	 * 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;
>> +
>> +	val = read_freq_feedback();
>> +	c->last_refclk_cnt = lower_32_bits(val);
>> +	c->last_coreclk_cnt = upper_32_bits(val);
>> +	udelay(c->delay);
>> +	val = read_freq_feedback();
>> +	c->refclk_cnt = lower_32_bits(val);
>> +	c->coreclk_cnt = upper_32_bits(val);
>> +}
>> +
>> +/*
>> + * 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_get_speed_common(u32 cpu, u32 delay)
>> +{
>> +	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;
>> +	read_counters_work.c.delay = delay;
>> +	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 unsigned int tegra194_get_speed(u32 cpu)
>> +{
>> +	return tegra194_get_speed_common(cpu, US_DELAY);
>> +}
>> +
>> +static unsigned int tegra194_fast_get_speed(u32 cpu)
>> +{
>> +	return tegra194_get_speed_common(cpu, US_DELAY_MIN);
>> +}
> 
> Personally, I would not bother with the above function as it is only
> used in one place.
> 
Kept the function for better readability. Ok, will open code it.

>> +
>> +static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
>> +{
>> +	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
>> +	int cl = get_cpu_cluster(policy->cpu);
>> +	u32 cpu;
>> +
>> +	if (cl >= data->num_clusters)
>> +		return -EINVAL;
>> +
>> +	policy->cur = tegra194_fast_get_speed(policy->cpu); /* boot freq */
>> +
>> +	/* set same policy for all cpus in a cluster */
>> +	for (cpu = (cl * 2); cpu < ((cl + 1) * 2); cpu++)
>> +		cpumask_set_cpu(cpu, policy->cpus);
>> +
>> +	policy->freq_table = data->tables[cl];
>> +	policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;
>> +
>> +	return 0;
>> +}
>> +
>> +static void set_cpu_ndiv(void *data)
>> +{
>> +	struct cpufreq_frequency_table *tbl = data;
>> +	u64 ndiv_val = (u64)tbl->driver_data;
>> +
>> +	asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
>> +}
>> +
>> +static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
>> +				       unsigned int index)
>> +{
>> +	struct cpufreq_frequency_table *tbl = policy->freq_table + index;
>> +
>> +	/*
>> +	 * 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.
>> +	 */
>> +	on_each_cpu_mask(policy->cpus, set_cpu_ndiv, tbl, true);
>> +
>> +	return 0;
>> +}
>> +
>> +static struct cpufreq_driver tegra194_cpufreq_driver = {
>> +	.name = "tegra194",
>> +	.flags = CPUFREQ_STICKY | 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 void tegra194_cpufreq_free_resources(void)
>> +{
>> +	destroy_workqueue(read_counters_wq);
>> +}
> 
> I would not bother with adding this function either.
> 
This function is used from remove call also.

>> +
>> +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);
>> +
>> +	/*
>> +	 * 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)
>> +{
>> +	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;
>> +
>> +	data->num_clusters = MAX_CLUSTERS;
>> +	data->tables = devm_kcalloc(&pdev->dev, data->num_clusters,
>> +				    sizeof(*data->tables), GFP_KERNEL);
>> +	if (!data->tables)
>> +		return -ENOMEM;
>> +
>> +	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->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 err_free_res;
> 
> You don't need the above if statement now you added the below.
> 
Sorry, missed to remove this. Will wait if any other comments before 
re-spin.

>> +
>> +	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", },
>> +	{ /* 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");
>>
> 
> Cheers
> Jon
> 

Re: [TEGRA194_CPUFREQ PATCH v6 3/3] cpufreq: Add Tegra194 cpufreq driver

[Viresh Kumar]

On 15-07-20, 20:57, Sumit Gupta wrote:
> Sorry, missed to remove this. Will wait if any other comments before
> re-spin.

I don't have any further comments, maybe just send a new version of
this patch alone and name it v6.1.

-- 
viresh

[TEGRA194_CPUFREQ PATCH v6.1 3/3] cpufreq: Add Tegra194 cpufreq driver

[Sumit Gupta]

Add support for CPU frequency scaling on Tegra194. The frequency
of each core can be adjusted by writing a clock divisor value to
a MSR on the core. The range of valid divisors is queried from
the BPMP.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 drivers/cpufreq/Kconfig.arm        |   7 +
 drivers/cpufreq/Makefile           |   1 +
 drivers/cpufreq/tegra194-cpufreq.c | 390 +++++++++++++++++++++++++++++++++++++
 3 files changed, 398 insertions(+)
 create mode 100644 drivers/cpufreq/tegra194-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 15c1a12..7e99a46 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -314,6 +314,13 @@ config ARM_TEGRA186_CPUFREQ
 	help
 	  This adds the CPUFreq driver support for Tegra186 SOCs.
 
+config ARM_TEGRA194_CPUFREQ
+	tristate "Tegra194 CPUFreq support"
+	depends on ARCH_TEGRA_194_SOC && TEGRA_BPMP
+	default y
+	help
+	  This adds CPU frequency driver support for Tegra194 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 f6670c4..66b5563 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_ARM_TANGO_CPUFREQ)		+= tango-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o
 obj-$(CONFIG_ARM_TEGRA186_CPUFREQ)	+= tegra186-cpufreq.o
+obj-$(CONFIG_ARM_TEGRA194_CPUFREQ)	+= tegra194-cpufreq.o
 obj-$(CONFIG_ARM_TI_CPUFREQ)		+= ti-cpufreq.o
 obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
 
diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
new file mode 100644
index 0000000..bae527e
--- /dev/null
+++ b/drivers/cpufreq/tegra194-cpufreq.c
@@ -0,0 +1,390 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020, 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 US_DELAY_MIN            2
+#define CPUFREQ_TBL_STEP_HZ     (50 * KHZ * KHZ)
+#define MAX_CNT                 ~0U
+
+/* cpufreq transisition latency */
+#define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */
+
+enum cluster {
+	CLUSTER0,
+	CLUSTER1,
+	CLUSTER2,
+	CLUSTER3,
+	MAX_CLUSTERS,
+};
+
+struct tegra194_cpufreq_data {
+	void __iomem *regs;
+	size_t num_clusters;
+	struct cpufreq_frequency_table **tables;
+};
+
+struct tegra_cpu_ctr {
+	u32 cpu;
+	u32 delay;
+	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;
+};
+
+static struct workqueue_struct *read_counters_wq;
+
+static enum cluster get_cpu_cluster(u8 cpu)
+{
+	return MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 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 tegra_read_counters(struct work_struct *work)
+{
+	struct read_counters_work *read_counters_work;
+	struct tegra_cpu_ctr *c;
+	u64 val;
+
+	/*
+	 * 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;
+
+	val = read_freq_feedback();
+	c->last_refclk_cnt = lower_32_bits(val);
+	c->last_coreclk_cnt = upper_32_bits(val);
+	udelay(c->delay);
+	val = read_freq_feedback();
+	c->refclk_cnt = lower_32_bits(val);
+	c->coreclk_cnt = upper_32_bits(val);
+}
+
+/*
+ * 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_get_speed_common(u32 cpu, u32 delay)
+{
+	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;
+	read_counters_work.c.delay = delay;
+	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 unsigned int tegra194_get_speed(u32 cpu)
+{
+	return tegra194_get_speed_common(cpu, US_DELAY);
+}
+
+static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+	int cl = get_cpu_cluster(policy->cpu);
+	u32 cpu;
+
+	if (cl >= data->num_clusters)
+		return -EINVAL;
+
+	/* boot freq */
+	policy->cur = tegra194_get_speed_common(policy->cpu, US_DELAY_MIN);
+
+	/* set same policy for all cpus in a cluster */
+	for (cpu = (cl * 2); cpu < ((cl + 1) * 2); cpu++)
+		cpumask_set_cpu(cpu, policy->cpus);
+
+	policy->freq_table = data->tables[cl];
+	policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;
+
+	return 0;
+}
+
+static void set_cpu_ndiv(void *data)
+{
+	struct cpufreq_frequency_table *tbl = data;
+	u64 ndiv_val = (u64)tbl->driver_data;
+
+	asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
+}
+
+static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
+				       unsigned int index)
+{
+	struct cpufreq_frequency_table *tbl = policy->freq_table + index;
+
+	/*
+	 * 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.
+	 */
+	on_each_cpu_mask(policy->cpus, set_cpu_ndiv, tbl, true);
+
+	return 0;
+}
+
+static struct cpufreq_driver tegra194_cpufreq_driver = {
+	.name = "tegra194",
+	.flags = CPUFREQ_STICKY | 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 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);
+
+	/*
+	 * 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)
+{
+	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;
+
+	data->num_clusters = MAX_CLUSTERS;
+	data->tables = devm_kcalloc(&pdev->dev, data->num_clusters,
+				    sizeof(*data->tables), GFP_KERNEL);
+	if (!data->tables)
+		return -ENOMEM;
+
+	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->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", },
+	{ /* 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");
-- 
2.7.4

Re: [TEGRA194_CPUFREQ PATCH v6 3/3] cpufreq: Add Tegra194 cpufreq driver

[Guenter Roeck]

On Wed, Jul 15, 2020 at 07:01:25PM +0530, Sumit Gupta wrote:
> Add support for CPU frequency scaling on Tegra194. The frequency
> of each core can be adjusted by writing a clock divisor value to
> a MSR on the core. The range of valid divisors is queried from
> the BPMP.
> 
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>

If built as module:

ERROR: modpost: "__cpu_logical_map" [drivers/cpufreq/tegra194-cpufreq.ko] undefined!

Guenter

Re: [TEGRA194_CPUFREQ PATCH v6 3/3] cpufreq: Add Tegra194 cpufreq driver

[Catalin Marinas]

On Sat, Aug 08, 2020 at 05:40:09PM -0700, Guenter Roeck wrote:
> On Wed, Jul 15, 2020 at 07:01:25PM +0530, Sumit Gupta wrote:
> > Add support for CPU frequency scaling on Tegra194. The frequency
> > of each core can be adjusted by writing a clock divisor value to
> > a MSR on the core. The range of valid divisors is queried from
> > the BPMP.
> > 
> > Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> > Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> 
> If built as module:
> 
> ERROR: modpost: "__cpu_logical_map" [drivers/cpufreq/tegra194-cpufreq.ko] undefined!

The exporting of this arm64 symbol went in last night.

-- 
Catalin