linux-kernel - Re: [PATCH v3 13/27] powerpc/powernv/pmem: Read the capability registers & wait for device ready

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Message-Id: <c6ce554a-62b4-2675-9ec3-1ded8eaacfc4@linux.ibm.com>
Date:   Thu, 27 Feb 2020 14:54:21 +1100
From:   Andrew Donnellan <ajd@...ux.ibm.com>
To:     "Alastair D'Silva" <alastair@....ibm.com>, alastair@...ilva.org
Cc:     "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        "Oliver O'Halloran" <oohall@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Frederic Barrat <fbarrat@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh@...nel.org>,
        Anton Blanchard <anton@...abs.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Cédric Le Goater <clg@...d.org>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kurz <groug@...d.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-nvdimm@...ts.01.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 13/27] powerpc/powernv/pmem: Read the capability
 registers & wait for device ready

On 21/2/20 2:27 pm, Alastair D'Silva wrote:
> +/**
> + * read_device_metadata() - Retrieve config information from the AFU and save it for future use
> + * @ocxlpmem: the device metadata
> + * Return: 0 on success, negative on failure
> + */
> +static int read_device_metadata(struct ocxlpmem *ocxlpmem)
> +{
> +	u64 val;
> +	int rc;
> +
> +	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu, GLOBAL_MMIO_CCAP0,
> +				     OCXL_LITTLE_ENDIAN, &val);
> +	if (rc)
> +		return rc;
> +
> +	ocxlpmem->scm_revision = val & 0xFFFF;
> +	ocxlpmem->read_latency = (val >> 32) & 0xFF;

This field is 16 bits in the spec, so the mask should be 0xFFFF I think?

Maybe we should generalise the EXTRACT_BITS macro we use in ocxl :)

-- 
Andrew Donnellan              OzLabs, ADL Canberra
ajd@...ux.ibm.com             IBM Australia Limited