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Message-ID: <0d523023-52e8-4154-2e5d-69d54458caa0@kernel.org>
Date: Tue, 3 Jul 2018 09:10:06 -0500
From: Timur Tabi <timur@...nel.org>
To: Vinod Koul <vkoul@...nel.org>, linux-crypto@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>,
Matt Mackall <mpm@...enic.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-arm-msm@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>,
Jeffrey Hugo <jhugo@...eaurora.org>
Subject: Re: [PATCH v3 6/6] crypto: qcom: Add ACPI support
On 7/3/18 1:04 AM, Vinod Koul wrote:
> Add support for probing on ACPI systems, with ACPI HID QCOM8160.
>
> On ACPI systems, clocks are always enabled, the PRNG should
> already be enabled, and the register region is read-only.
> The driver only verifies that the hardware is already
> enabled never tries to disable or configure it.
>
> Signed-off-by: Timur Tabi<timur@...eaurora.org>
> [port to crypto API]
> Signed-off-by: Vinod Koul<vkoul@...nel.org>
I've asked a colleague who still works at Qualcomm to test this code on
silicon. It looks okay, but I just want to be sure.
> + /*
> + * ACPI systems have v2 hardware. The clocks are always enabled,
> + * the PRNG register space is read-only and the PRNG should
> + * already be enabled.
> + */
> + if (has_acpi_companion(&pdev->dev)) {
> + val = readl(rng->base + PRNG_CONFIG);
> + if (!(val & PRNG_CONFIG_HW_ENABLE)) {
> + dev_err(&pdev->dev, "device is not enabled\n");
> + return -ENODEV;
> + }
I'm having second thoughts about this PRNG_CONFIG_HW_ENABLE check. The
PRNG on the QDF2400 is the same as the one on the 8996, so it should
have the same register interface. Currently, the ACPI table points to a
full PRNG register block, but I'm beginning to believe that it should
instead point to a "reduced" block that doesn't have a PRNG_CONFIG register.
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