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Tue, 07 Oct 2025 00:11:10 -0700 (PDT) Message-ID: <793a00d6-a1ae-4928-a326-3d276a30bdbd@gmail.com> Date: Tue, 7 Oct 2025 00:09:50 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 05/11] rvtrace: Add trace encoder driver To: Anup Patel , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Paul Walmsley , Palmer Dabbelt , Greg KH , Alexander Shishkin , Ian Rogers Cc: Mark Rutland , devicetree@vger.kernel.org, Alexandre Ghiti , Atish Patra , Peter Zijlstra , Anup Patel , Adrian Hunter , linux-kernel@vger.kernel.org, Mayuresh Chitale , Ingo Molnar , Jiri Olsa , Mayuresh Chitale , Namhyung Kim , linux-riscv@lists.infradead.org, Andrew Jones , Liang Kan References: <20251002060732.100213-1-apatel@ventanamicro.com> <20251002060732.100213-6-apatel@ventanamicro.com> Content-Language: en-US From: Bo Gan In-Reply-To: <20251002060732.100213-6-apatel@ventanamicro.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/1/25 23:07, Anup Patel wrote: > From: Mayuresh Chitale > > Add initial implementation of RISC-V trace encoder driver. The encoder > is defined in the RISC-V Trace Control Interface specification. > > Co-developed-by: Anup Patel > Signed-off-by: Anup Patel > Signed-off-by: Mayuresh Chitale > --- > drivers/hwtracing/rvtrace/Kconfig | 7 ++ > drivers/hwtracing/rvtrace/Makefile | 1 + > drivers/hwtracing/rvtrace/rvtrace-encoder.c | 107 ++++++++++++++++++++ > 3 files changed, 115 insertions(+) > create mode 100644 drivers/hwtracing/rvtrace/rvtrace-encoder.c > > diff --git a/drivers/hwtracing/rvtrace/Kconfig b/drivers/hwtracing/rvtrace/Kconfig > index f8f6feea1953..ba35c05f3f54 100644 > --- a/drivers/hwtracing/rvtrace/Kconfig > +++ b/drivers/hwtracing/rvtrace/Kconfig > @@ -14,3 +14,10 @@ menuconfig RVTRACE > > To compile this driver as a module, choose M here: the module > will be called rvtrace. > + > +config RVTRACE_ENCODER > + tristate "RISC-V Trace Encoder driver" > + depends on RVTRACE > + default y > + help > + This driver provides support for RISC-V Trace Encoder component. > diff --git a/drivers/hwtracing/rvtrace/Makefile b/drivers/hwtracing/rvtrace/Makefile > index 988525a379cf..f320693a1fc5 100644 > --- a/drivers/hwtracing/rvtrace/Makefile > +++ b/drivers/hwtracing/rvtrace/Makefile > @@ -2,3 +2,4 @@ > > obj-$(CONFIG_RVTRACE) += rvtrace.o > rvtrace-y := rvtrace-core.o rvtrace-platform.o > +obj-$(CONFIG_RVTRACE_ENCODER) += rvtrace-encoder.o > diff --git a/drivers/hwtracing/rvtrace/rvtrace-encoder.c b/drivers/hwtracing/rvtrace/rvtrace-encoder.c > new file mode 100644 > index 000000000000..45d1c5b12c51 > --- /dev/null > +++ b/drivers/hwtracing/rvtrace/rvtrace-encoder.c > @@ -0,0 +1,107 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (c) 2025 Ventana Micro Systems Inc. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define RVTRACE_COMPONENT_CTRL_ITRACE_MASK 0x1 > +#define RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT 2 > +#define RVTRACE_COMPONENT_CTRL_INSTMODE_MASK 0x7 > +#define RVTRACE_COMPONENT_CTRL_INSTMODE_SHIFT 4 > + > +static int rvtrace_encoder_start(struct rvtrace_component *comp) > +{ > + u32 val; > + > + val = rvtrace_read32(comp->pdata, RVTRACE_COMPONENT_CTRL_OFFSET); > + val |= BIT(RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT); > + rvtrace_write32(comp->pdata, val, RVTRACE_COMPONENT_CTRL_OFFSET); > + return rvtrace_poll_bit(comp->pdata, RVTRACE_COMPONENT_CTRL_OFFSET, > + RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT, 1, > + comp->pdata->control_poll_timeout_usecs); > +} > + > +static int rvtrace_encoder_stop(struct rvtrace_component *comp) > +{ > + u32 val; > + > + val = rvtrace_read32(comp->pdata, RVTRACE_COMPONENT_CTRL_OFFSET); > + val &= ~BIT(RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT); > + rvtrace_write32(comp->pdata, val, RVTRACE_COMPONENT_CTRL_OFFSET); > + return rvtrace_poll_bit(comp->pdata, RVTRACE_COMPONENT_CTRL_OFFSET, > + RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT, 0, > + comp->pdata->control_poll_timeout_usecs); > +} > + > +static void rvtrace_encoder_setmode(struct rvtrace_component *comp, u32 mode) > +{ > + u32 val; > + > + val = rvtrace_read32(comp->pdata, RVTRACE_COMPONENT_CTRL_OFFSET); > + val |= (mode << RVTRACE_COMPONENT_CTRL_INSTMODE_SHIFT); > + rvtrace_write32(comp->pdata, val, RVTRACE_COMPONENT_CTRL_OFFSET); > +} > + > +static int rvtrace_encoder_probe(struct rvtrace_component *comp) > +{ > + int ret; > + > + rvtrace_encoder_setmode(comp, 0x6); > + ret = rvtrace_enable_component(comp); > + if (ret) > + return dev_err_probe(&comp->dev, ret, "failed to enable encoder.\n"); > + > + return 0; > +} Trace components needs proper probing before use. Refer to Control Interface Spec: https://github.com/riscv-non-isa/tg-nexus-trace/releases/download/1.0_Ratified/RISC-V-Trace-Control-Interface.pdf Chapter 5. This versioning applies to all components, e.g., sinks/funnels... The driver should check the HW impl version with what it supports, and rejects registering the component(s) if not supported. Chapter 5. has more details. > + > +static void rvtrace_encoder_remove(struct rvtrace_component *comp) > +{ > + int ret; > + > + ret = rvtrace_disable_component(comp); > + if (ret) > + dev_err(&comp->dev, "failed to disable encoder.\n"); > +} > + > +static struct rvtrace_component_id rvtrace_encoder_ids[] = { > + { .type = RVTRACE_COMPONENT_TYPE_ENCODER, > + .version = rvtrace_component_mkversion(1, 0), }, > + {}, > +}; > + > +static struct rvtrace_driver rvtrace_encoder_driver = { > + .id_table = rvtrace_encoder_ids, > + .start = rvtrace_encoder_start, > + .stop = rvtrace_encoder_stop, > + .probe = rvtrace_encoder_probe, > + .remove = rvtrace_encoder_remove, > + .driver = { > + .name = "rvtrace-encoder", > + }, > +}; > + > +static int __init rvtrace_encoder_init(void) > +{ > + return rvtrace_register_driver(&rvtrace_encoder_driver); > +} > + > +static void __exit rvtrace_encoder_exit(void) > +{ > + rvtrace_unregister_driver(&rvtrace_encoder_driver); > +} > + > +module_init(rvtrace_encoder_init); > +module_exit(rvtrace_encoder_exit); > + > +/* Module information */ > +MODULE_AUTHOR("Mayuresh Chitale "); > +MODULE_DESCRIPTION("RISC-V Trace Encoder Driver"); > +MODULE_LICENSE("GPL"); Bo