linux-kernel - Re: [PATCH v6 2/5] remoteproc: qcom: Introduce helper to store pil info in IMEM

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Message-ID: <159056097743.88029.16084555679084078794@swboyd.mtv.corp.google.com>
Date:   Tue, 26 May 2020 23:29:37 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>
Cc:     Rob Herring <robh+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Vinod Koul <vkoul@...nel.org>
Subject: Re: [PATCH v6 2/5] remoteproc: qcom: Introduce helper to store pil info in IMEM

Quoting Bjorn Andersson (2020-05-26 22:48:46)
> diff --git a/drivers/remoteproc/qcom_pil_info.c b/drivers/remoteproc/qcom_pil_info.c
> new file mode 100644
> index 000000000000..0785c7cde2d3
> --- /dev/null
> +++ b/drivers/remoteproc/qcom_pil_info.c
> @@ -0,0 +1,124 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2019-2020 Linaro Ltd.
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_address.h>
> +
> +#define PIL_RELOC_NAME_LEN     8
> +
> +struct pil_reloc_entry {
> +       char name[PIL_RELOC_NAME_LEN];
> +       __le64 base;
> +       __le32 size;
> +} __packed;
> +
> +struct pil_reloc {
> +       struct device *dev;

This isn't assigned. Remove it?

> +       void __iomem *base;
> +       size_t num_entries;
> +};
> +
> +static struct pil_reloc _reloc __read_mostly;
> +static DEFINE_MUTEX(reloc_mutex);

reloc_mutex is a little generic. Maybe pil_reloc_lock or
qcom_pil_reloc_lock?

> +
> +static int qcom_pil_info_init(void)
> +{
> +       struct device_node *np;
> +       struct resource imem;
> +       void __iomem *base;
> +       int ret;
> +
> +       /* Already initialized? */
> +       if (_reloc.base)
> +               return 0;
> +
> +       np = of_find_compatible_node(NULL, NULL, "qcom,pil-reloc-info");
> +       if (!np)
> +               return -ENOENT;
> +
> +       ret = of_address_to_resource(np, 0, &imem);
> +       of_node_put(np);
> +       if (ret < 0)
> +               return ret;
> +
> +       base = ioremap(imem.start, resource_size(&imem));
> +       if (!base) {
> +               pr_err("failed to map PIL relocation info region\n");
> +               return -ENOMEM;
> +       }
> +
> +       memset_io(base, 0, resource_size(&imem));
> +
> +       _reloc.base = base;
> +       _reloc.num_entries = resource_size(&imem) / sizeof(struct pil_reloc_entry);
> +
> +       return 0;
> +}
> +
> +/**
> + * qcom_pil_info_store() - store PIL information of image in IMEM
> + * @image:     name of the image
> + * @base:      base address of the loaded image
> + * @size:      size of the loaded image
> + *
> + * Return: 0 on success, negative errno on failure
> + */
> +int qcom_pil_info_store(const char *image, phys_addr_t base, size_t size)
> +{
> +       char buf[PIL_RELOC_NAME_LEN];
> +       void __iomem *entry;
> +       int ret;
> +       int i;
> +
> +       mutex_lock(&reloc_mutex);
> +       ret = qcom_pil_info_init();
> +       if (ret < 0) {
> +               mutex_unlock(&reloc_mutex);
> +               return ret;
> +       }
> +
> +       for (i = 0; i < _reloc.num_entries; i++) {
> +               entry = _reloc.base + i * sizeof(struct pil_reloc_entry);
> +
> +               memcpy_fromio(buf, entry, PIL_RELOC_NAME_LEN);
> +
> +               /*
> +                * An empty record means we didn't find it, given that the
> +                * records are packed.
> +                */
> +               if (!buf[0])
> +                       goto found_unused;
> +
> +               if (!strncmp(buf, image, PIL_RELOC_NAME_LEN))
> +                       goto found_existing;
> +       }
> +
> +       pr_warn("insufficient PIL info slots\n");
> +       mutex_unlock(&reloc_mutex);
> +       return -ENOMEM;
> +
> +found_unused:
> +       memcpy_toio(entry, image, PIL_RELOC_NAME_LEN);
> +found_existing:
> +       writel(base, entry + offsetof(struct pil_reloc_entry, base));
> +       writel(size, entry + offsetof(struct pil_reloc_entry, size));

It makes me nervous to see offsetof() used in the same line as writel()
because who knows what the compiler does, even with __packed and stuff.
I guess I tried and failed to convince you earlier to change this code
to use fixed offsets instead of structs to describe the memory layout
but that must have failed!

> +       mutex_unlock(&reloc_mutex);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(qcom_pil_info_store);
> +
> +static void __exit pil_reloc_exit(void)
> +{
> +       mutex_lock(&reloc_mutex);
> +       iounmap(_reloc.base);
> +       _reloc.base = NULL;
> +       mutex_unlock(&reloc_mutex);
> +}
> +module_exit(pil_reloc_exit);
> +
> +MODULE_DESCRIPTION("Qualcomm PIL relocation info");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/remoteproc/qcom_pil_info.h b/drivers/remoteproc/qcom_pil_info.h
> new file mode 100644
> index 000000000000..1b89a63ba82f
> --- /dev/null
> +++ b/drivers/remoteproc/qcom_pil_info.h
> @@ -0,0 +1,7 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __QCOM_PIL_INFO_H__
> +#define __QCOM_PIL_INFO_H__

Probably need <linux/types.h> here for phys_addr_t definition to make
this header self-contained.

> +
> +int qcom_pil_info_store(const char *image, phys_addr_t base, size_t size);
> +
> +#endif