From patchwork Sat Nov 18 10:44:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhang Xiaoxu X-Patchwork-Id: 745608 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9BDC7C5AE5C for ; Sat, 18 Nov 2023 10:45:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232457AbjKRKph (ORCPT ); Sat, 18 Nov 2023 05:45:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229716AbjKRKpf (ORCPT ); Sat, 18 Nov 2023 05:45:35 -0500 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F10610DA; Sat, 18 Nov 2023 02:45:31 -0800 (PST) Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4SXVm73l0yz4f3kFr; Sat, 18 Nov 2023 18:45:27 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 0C4761A016E; Sat, 18 Nov 2023 18:45:29 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.101.107]) by APP1 (Coremail) with SMTP id cCh0CgBXWhDClVhlAjMGBQ--.58652S8; Sat, 18 Nov 2023 18:45:28 +0800 (CST) From: Zhang Xiaoxu To: zhangxiaoxu5@huawei.com, weiyongjun1@huawei.com, linux-kernel@vger.kernel.org, broonie@kernel.org, rostedt@goodmis.org, mingo@redhat.com, frowand.list@gmail.com, linux-spi@vger.kernel.org Subject: [PATCH v4 -next 4/4] spi: mockup: Add documentation Date: Sat, 18 Nov 2023 18:44:42 +0800 Message-Id: <20231118104442.861759-5-zhangxiaoxu@huawecloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231118104442.861759-1-zhangxiaoxu@huawecloud.com> References: <20231118104442.861759-1-zhangxiaoxu@huawecloud.com> MIME-Version: 1.0 X-CM-TRANSID: cCh0CgBXWhDClVhlAjMGBQ--.58652S8 X-Coremail-Antispam: 1UD129KBjvJXoW3Wry5Jr4xWFW7Jry5WFWkCrg_yoW7trWDpF WUJFy3K3y8XF9xWF1Sq3s5G343Aas7ZFZrGFZ5tF10yr1q9r95AF1xtryYqan8WF4DCFy0 vFW5AFW8Kry7Z3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBSb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW7JVWDJwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E 14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7 xfMcIj6xIIjxv20xvE14v26r1Y6r17McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Y z7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41l42xK82IYc2Ij64vIr41l42xK82IY64kExVAvwV Aq07x20xyl4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s02 6x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0x vE2Ix0cI8IcVAFwI0_Gr0_Xr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1lIxAI cVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r4j6F4UMIIF0xvEx4A2js IEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuYvjxUruWlDUUUU Sender: zhangxiaoxu@huaweicloud.com X-CM-SenderInfo: x2kd0wp0ld053x6k3tpzhluzxrxghudrp/ Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org From: Zhang Xiaoxu Add documentation for the SPI mockup controller driver. This include the tutorial for how to mockup a spi device. Signed-off-by: Wei Yongjun Signed-off-by: Zhang Xiaoxu --- Documentation/spi/index.rst | 1 + Documentation/spi/spi-mockup.rst | 198 +++++++++++++++++++++++++++++++ 2 files changed, 199 insertions(+) create mode 100644 Documentation/spi/spi-mockup.rst diff --git a/Documentation/spi/index.rst b/Documentation/spi/index.rst index 06c34ea11bcf..a8f4f5cd0f09 100644 --- a/Documentation/spi/index.rst +++ b/Documentation/spi/index.rst @@ -13,6 +13,7 @@ Serial Peripheral Interface (SPI) pxa2xx spi-lm70llp spi-sc18is602 + spi-mockup .. only:: subproject and html diff --git a/Documentation/spi/spi-mockup.rst b/Documentation/spi/spi-mockup.rst new file mode 100644 index 000000000000..a5b69ce83ad9 --- /dev/null +++ b/Documentation/spi/spi-mockup.rst @@ -0,0 +1,198 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========== +spi-mockup +========== + +Description +=========== + +This module is a very simple fake SPI controller driver. It implements +a BPF based interface to mockup SPI device. + +No hardware is needed nor associated with this module. It will respond +spi message by BPF program attached to spi_transfer_writeable tracepoint +by reading from or writing BPF maps. + +The typical use-case is like this: + 1. create the spi mockup controller; + 2. load EBPF program as device's backend; + 3. create target chip device to the spi mockup controller. + +Example +======= + +This example show how to mock a MTD device by using spi-mockup driver. + +Compile your copy of the kernel source. Make sure to configure the spi-mockup +and the target chip driver as a module. + +Register the spi mockup controller. + +:: + + $ mkdir /sys/kernel/config/spi-mockup/spi0 + + # configure the spi mockup controller attribute + $ echo 40000 > /sys/kernel/config/spi-mockup/spi0/min_speed + $ echo 25000000 > /sys/kernel/config/spi-mockup/spi0/max_speed + $ echo 0 > /sys/kernel/config/spi-mockup/spi0/flags + $ echo 8 > /sys/kernel/config/spi-mockup/spi0/num_cs + + # enable the spi mockup controller + $ echo 1 > /sys/kernel/config/spi-mockup/spi0/live + +Write a BPF program as device's backup. + +:: + + #define MCHP23K256_CMD_WRITE_STATUS 0x01 + #define MCHP23K256_CMD_WRITE 0x02 + #define MCHP23K256_CMD_READ 0x03 + + #define CHIP_REGS_SIZE 0x20000 + + #define MAX_CMD_SIZE 4 + + struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, CHIP_REGS_SIZE); + __type(key, __u32); + __type(value, __u8); + } regs_mchp23k256 SEC(".maps"); + + static unsigned int chip_reg = 0; + + static int spi_transfer_read(struct spi_msg_ctx *msg, unsigned int len) + { + int i, key; + u8 *reg; + + for (i = 0; i < len && i < sizeof(msg->data); i++) { + key = i + chip_reg; + + reg = bpf_map_lookup_elem(®s_mchp23k256, &key); + if (!reg) { + bpf_printk("key %d not exists", key); + return -EINVAL; + } + + msg->data[i] = *reg; + } + + return 0; + } + + static int spi_transfer_write(struct spi_msg_ctx *msg, unsigned int len) + { + u8 opcode = msg->data[0], value; + int i, key; + + switch (opcode) { + case MCHP23K256_CMD_READ: + case MCHP23K256_CMD_WRITE: + if (len < 2) + return -EINVAL; + + chip_reg = 0; + for (i = 0; i < MAX_CMD_SIZE && i < len - 1; i++) + chip_reg = (chip_reg << 8) + msg->data[1 + i]; + + return 0; + case MCHP23K256_CMD_WRITE_STATUS: + // ignore write status + return 0; + default: + break; + } + + for (i = 0; i < len && i < sizeof(msg->data); i++) { + value = msg->data[i]; + key = chip_reg + i; + + if (bpf_map_update_elem(®s_mchp23k256, &key, &value, + BPF_EXIST)) { + bpf_printk("key %d not exists", key); + return -EINVAL; + } + } + + return 0; + } + + SEC("raw_tp.w/spi_transfer_writeable") + int BPF_PROG(mtd_mchp23k256, struct spi_msg_ctx *msg, u8 chip, unsigned int len) + { + int ret = 0; + + if (msg->tx_nbits) + ret = spi_transfer_write(msg, len); + else if (msg->rx_nbits) + ret = spi_transfer_read(msg, len); + + return ret; + } + + char LICENSE[] SEC("license") = "GPL"; + +Use bpftool to load the BPF program. + +:: + + $ bpftool prog load mtd-mchp23k256.o /sys/fs/bpf/mtd_mchp23k256 autoattach + +Create the mchp23k256 device, this is accomplished by executing the +following command: + +:: + + $ mkdir /sys/kernel/config/spi-mockup/spi0/targets/mchp23k256 + $ echo -n mchp23k256 > /sys/kernel/config/spi-mockup/spi0/targets/mchp23k256/device_id + $ echo 1 > /sys/kernel/config/spi-mockup/spi0/targets/mchp23k256/live + + +Now, the mchp23k256 MTD device named /dev/mtd0 has been created successfully. + +:: + + $ ls /sys/bus/spi/devices/spi0.0/mtd/ + mtd0 mtd0ro + + $ cat /sys/class/mtd/mtd0/name + spi0.0 + + $ hexdump /dev/mtd0 + 0000000 0000 0000 0000 0000 0000 0000 0000 0000 + * + 0008000 + + $ echo aaaa > /dev/mtd0 + + $ hexdump /dev/mtd0 + 00000000 61 61 61 61 0a 00 00 00 00 00 00 00 00 00 00 00 |aaaa............| + 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| + * + 00008000 + + $ bpftool map update name regs_mchp23k256 key 0 0 0 0 value 0 + + $ hexdump /dev/mtd0 + 00000000 00 61 61 61 0a 00 00 00 00 00 00 00 00 00 00 00 |.aaa............| + 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| + * + 00008000 + + +Remove the mchp23k256 device by executing the following command: + +:: + + $ echo 0 > /sys/kernel/config/spi-mockup/spi0/targets/mchp23k256/live + $ rmdir /sys/kernel/config/spi-mockup/spi0/targets/mchp23k256 + +Remove the spi mockup controller by executing the following command: + +:: + + $ echo 0 > /sys/kernel/config/spi-mockup/spi0/live + $ rmdir /sys/kernel/config/spi-mockup/spi0