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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cddc186fc72sm756387a12.5.2026.11.12.22.27.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Nov 2026 22:27:32 -0800 (PST) Message-ID: <4f680a92-c69c-459b-acc1-c877e88cc265@oss.qualcomm.com> Date: Fri, 13 Nov 2026 14:27:27 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 8/9] cpufreq: tegra194: Add support for Tegra264 To: Sumit Gupta , rafael@kernel.org, viresh.kumar@linaro.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, treding@nvidia.com, jonathanh@nvidia.com, linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Cc: bbasu@nvidia.com, Zhongqiu Han References: <20261104181521.3003578-1-sumitg@nvidia.com> <20261104181521.3003578-9-sumitg@nvidia.com> Content-Language: en-US From: Zhongqiu Han In-Reply-To: <20261104181521.3003578-9-sumitg@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: oiv0m9lWaj3m7v-S_WYoREa_zW9Wj9_e X-Proofpoint-Spam-Info: AW1haW4tMjYxMTEzMDAyNSBTYWx0ZWRfXyTDI3h6MV1S7 hCaO5jWpEbqT7M6AcVi/To2zDvxhbU+CspXTSLODN/vyqGD2dWHu+RaB/4bwiLKu8Ay1nGrcH62 eYiwo8/xPiFtSJoA+Lz7Xia/NQs2qnw= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTEzMDAyNSBTYWx0ZWRfXySmX7+7FUZ3X LoqLSBKCLPakilfTelSpWLTOGAHsy3e3lcACl7s+5EKzLo0FmAEfQhApMHwqqo2c9L91/BTpqgN 04LzfvjSzvitTh5ue2XQVgpPBql55Sk4P6FEePGe7UBxNtrq/1bSX/ext1EpD1DAmYxyiwIKX65 azm+IrkbZlNqQc832AoligW5otz1M8zgz4TwXhG432jJeUdVHvuTXA9vv0Wn7FWYLyBtnaKNwEa a+yaiD2Ycp8xATus2JcAHSWps+DoCqplxpPq2s1yE2Ycst/C5IwfA9UM1pCS8erd2i3hxnqwt/W FeUL5odW3QkIfpDMO2OuhfZwEeGj53RuHKqKCNnt2C2Rq2TEShTkeMKW5hnx/rcsNwfCPisEhpi 65BUjbLJTmKk0VUp++VUXlh0XuEJ7/+uGpUVbEKxxp+ivnzPJAJ2pO2oXwliSNIUm9GZYns/pTR /cZDsRwpOw97z45Zb0Q== X-Proofpoint-ORIG-GUID: oiv0m9lWaj3m7v-S_WYoREa_zW9Wj9_e X-Authority-Analysis: v=2.4 cv=AoN7T+9P c=1 sm=1 tr=0 ts=6af6add6 cx=c_pps a=cmESyDAEBpBGqyK7t0alAg==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=zJRp6_cAMcgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_K5XuSEh1TEqbUxoQ0s3:22 a=Ikd4Dj_1AAAA:8 a=xaSE4ohpd0vWBzKOhacA:9 a=QEXdDO2ut3YA:10 a=1OuFwYUASf3TG4hYMiVC:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-13_02,2026-11-11_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 phishscore=0 suspectscore=0 spamscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2611040001 definitions=main-2611130025 On 11/5/2026 2:15 AM, Sumit Gupta wrote: > Add cpufreq support for Tegra264. It requests and reads the CPU > frequency differently from earlier SoCs. > > To request a frequency, the driver writes NDIV to a core_freq_req > register in the CCPLEX register space. Two clusters share a > cluster-clock unit and its register, so they always run at the same > frequency. The driver exposes each pair as one performance domain and > one cpufreq policy. Each CPU's "performance-domains" property gives the > domain index, which selects the register. If the CCPLEX node declares > "#performance-domain-cells", probe fails if any CPU lacks the property. > > To read the frequency, the driver samples the per-CPU 64-bit AMU > counters through system registers. The AMU constant counter is the > reference. It ticks at the system counter rate, so the driver takes the > reference rate from CNTFRQ instead of the fixed 408 MHz clock. > > Signed-off-by: Sumit Gupta > --- > drivers/cpufreq/Kconfig.arm | 4 +- > drivers/cpufreq/tegra194-cpufreq.c | 147 ++++++++++++++++++++++++++++- > 2 files changed, 144 insertions(+), 7 deletions(-) > > diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm > index a441668f9e0c..a5482b12be57 100644 > --- a/drivers/cpufreq/Kconfig.arm > +++ b/drivers/cpufreq/Kconfig.arm > @@ -248,9 +248,9 @@ config ARM_TEGRA186_CPUFREQ > > config ARM_TEGRA194_CPUFREQ > tristate "Tegra194 CPUFreq support" > - depends on ARCH_TEGRA_194_SOC || ARCH_TEGRA_234_SOC > + depends on ARCH_TEGRA_194_SOC || ARCH_TEGRA_234_SOC || ARCH_TEGRA_264_SOC > depends on TEGRA_BPMP > - default ARCH_TEGRA_194_SOC || ARCH_TEGRA_234_SOC > + default ARCH_TEGRA_194_SOC || ARCH_TEGRA_234_SOC || ARCH_TEGRA_264_SOC > help > This adds CPU frequency driver support for Tegra194 SOCs. > > diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c > index 1328aa0a1bd1..0767a6fd6bdc 100644 > --- a/drivers/cpufreq/tegra194-cpufreq.c > +++ b/drivers/cpufreq/tegra194-cpufreq.c > @@ -14,7 +14,9 @@ > #include > #include > > +#include > #include > +#include > > #include > #include > @@ -36,6 +38,18 @@ > (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)) > > +/* > + * Tegra264 requests a frequency by writing the NDIV to a core_freq_req > + * register in the CCPLEX register space. > + * > + * Two clusters that share a cluster-clock unit form a performance domain. > + * Each domain has one core_freq_req register. The registers are grouped > + * in blocks, two domains per block. > + */ > +#define T264_CORE_FREQ_REQ_BLOCK_SIZE 0x400000 > +#define T264_CORE_FREQ_REQ_BLOCK_DOMAIN0_OFFSET 0x40000 > +#define T264_CORE_FREQ_REQ_BLOCK_DOMAIN1_OFFSET 0x50000 > + > /* cpufreq transisition latency */ > #define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */ > > @@ -70,6 +84,8 @@ struct tegra_cpufreq_ops { > struct tegra_cpufreq_soc { > struct tegra_cpufreq_ops *ops; > u64 cnt_mask; > + /* AMU's constant counter ticks at the system counter rate. */ > + bool ref_clk_from_cntfrq; > int maxcpus_per_cluster; > unsigned int num_clusters; > bool needs_mmio; > @@ -79,8 +95,10 @@ struct tegra_cpufreq_soc { > > struct tegra194_cpufreq_data { > void __iomem *regs; > + resource_size_t regs_size; > struct cpufreq_frequency_table **bpmp_luts; > const struct tegra_cpufreq_soc *soc; > + u32 ref_clk_mhz; > bool icc_dram_bw_scaling; > struct tegra_cpu_data *cpu_data; > enum cpuhp_state cpuhp_state; > @@ -240,6 +258,78 @@ static const struct tegra_cpufreq_soc tegra238_cpufreq_soc = { > .refclk_delta_min = 16000, > }; > > +static void __iomem *tegra264_core_freq_req_reg(struct tegra194_cpufreq_data *data, > + u32 clkid) > +{ > + u64 offset = (u64)(clkid / 2) * T264_CORE_FREQ_REQ_BLOCK_SIZE; > + > + offset += (clkid % 2) ? T264_CORE_FREQ_REQ_BLOCK_DOMAIN1_OFFSET : > + T264_CORE_FREQ_REQ_BLOCK_DOMAIN0_OFFSET; > + > + /* > + * clkid comes from the device tree. Reject an index whose 32-bit > + * register does not fit in the mapped region. > + */ > + if (offset + sizeof(u32) > data->regs_size) > + return NULL; > + > + return data->regs + offset; > +} > + > +static int tegra264_get_cpu_ndiv(u32 cpu, u32 cpuid, u32 clusterid, u64 *ndiv) > +{ > + struct tegra194_cpufreq_data *data = cpufreq_get_driver_data(); > + u32 clkid = data->cpu_data[cpu].clkid; > + void __iomem *reg; > + > + reg = tegra264_core_freq_req_reg(data, clkid); > + if (!reg) > + return -EINVAL; > + > + *ndiv = readl(reg) & NDIV_MASK; > + > + return 0; > +} > + > +static void tegra264_set_cpu_ndiv(struct cpufreq_policy *policy, u64 ndiv) > +{ > + struct tegra194_cpufreq_data *data = cpufreq_get_driver_data(); > + u32 clkid = data->cpu_data[policy->cpu].clkid; > + void __iomem *reg; > + > + reg = tegra264_core_freq_req_reg(data, clkid); > + if (reg) > + writel(ndiv, reg); > +} > + > +/* > + * The AMU counters are per-CPU system registers, so this must run on the CPU > + * it samples. tegra194_calculate_speed() queues it there with queue_work_on(). > + */ > +static void tegra264_sample_counters(struct tegra194_cpufreq_data *data, > + struct tegra_cpu_ctr *c) > +{ > + c->coreclk_cnt = read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0); > + c->refclk_cnt = read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0); AMU is optional, so arm64 core reads these counters only with CONFIG_ARM64_AMU_EXTN and a per-CPU check (arch/arm64/kernel/ topology.c). Is AMU always enabled on Tegra264, or should this be gated the same way? -- Thx and BRs, Zhongqiu Han