linux-kernel - Re: [PATCH v3 3/4] nvmem: qfprom: Add fuse blowing support

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Date:   Wed, 17 Jun 2020 09:03:16 -0600
From:   Jeffrey Hugo <jhugo@...eaurora.org>
To:     Douglas Anderson <dianders@...omium.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>
Cc:     dhavalp@...eaurora.org, mturney@...eaurora.org,
        rnayak@...eaurora.org, Ravi Kumar Bokka <rbokka@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, saiprakash.ranjan@...eaurora.org,
        sparate@...eaurora.org, mkurumel@...eaurora.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] nvmem: qfprom: Add fuse blowing support

On 6/17/2020 8:51 AM, Douglas Anderson wrote:
> From: Ravi Kumar Bokka <rbokka@...eaurora.org>
> 
> This patch adds support for blowing fuses to the qfprom driver if the
> required properties are defined in the device tree.
> 
> Signed-off-by: Ravi Kumar Bokka <rbokka@...eaurora.org>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
> Please double-check that I got the major/minor version logic right
> here.  I don't have documentation for this, but Srinivas mentioned
> that it was at address 0x6000 and I happened to find an "8" and a "7"
> on sc7180 so I assumed that was the major and minor version.
> 
> Changes in v3:
> - Don't provide "reset" value for things; just save/restore.
> - Use the major/minor version read from 0x6000.
> - Reading should still read "corrected", not "raw".
> - Added a sysfs knob to allow you to read "raw" instead of "corrected"
> - Simplified the SoC data structure.
> - No need for quite so many levels of abstraction for clocks/regulator.
> - Don't set regulator voltage.  Rely on device tree to make sure it's right.
> - Properly undo things in the case of failure.
> - Don't just keep enabling the regulator over and over again.
> - Enable / disable the clock each time
> - Polling every 100 us but timing out in 10 us didn't make sense; swap.
> - No reason for 100 us to be SoC specific.
> - No need for reg-names.
> - We shouldn't be creating two separate nvmem devices.
> 
>   drivers/nvmem/qfprom.c | 314 +++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 303 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/nvmem/qfprom.c b/drivers/nvmem/qfprom.c
> index 8a91717600be..486202860f84 100644
> --- a/drivers/nvmem/qfprom.c
> +++ b/drivers/nvmem/qfprom.c
> @@ -3,57 +3,349 @@
>    * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>    */
>   
> +#include <linux/clk.h>
>   #include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/kernel.h>
>   #include <linux/module.h>
>   #include <linux/mod_devicetable.h>
> -#include <linux/io.h>
>   #include <linux/nvmem-provider.h>
>   #include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +
> +/* Blow timer clock frequency in Mhz */
> +#define QFPROM_BLOW_TIMER_OFFSET 0x03c
> +
> +/* Amount of time required to hold charge to blow fuse in micro-seconds */
> +#define QFPROM_FUSE_BLOW_POLL_US	10
> +#define QFPROM_FUSE_BLOW_TIMEOUT_US	100
> +
> +#define QFPROM_BLOW_STATUS_OFFSET	0x048
> +#define QFPROM_BLOW_STATUS_BUSY		0x1
> +#define QFPROM_BLOW_STATUS_READY	0x0
> +
> +#define QFPROM_ACCEL_OFFSET		0x044
> +
> +#define QFPROM_VERSION_OFFSET		0x0
> +#define QFPROM_MAJOR_VERSION_SHIFT	28
> +#define QFPROM_MAJOR_VERSION_MASK	0xf
> +#define QFPROM_MINOR_VERSION_SHIFT	16
> +#define QFPROM_MINOR_VERSION_MASK	0xf

Minor looks wrong.  Documentation says bits 27:16 are the minor version, 
and bits 15:0 are step.  I think your minor mask needs to be 0xfff.

-- 
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.