From: Leonard Crestez <leonard.crestez@nxp.com>
To: "l.stach@pengutronix.de" <l.stach@pengutronix.de>,
Abel Vesa <abel.vesa@nxp.com>, Anson Huang <anson.huang@nxp.com>
Cc: dl-linux-imx <linux-imx@nxp.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Fabio Estevam <fabio.estevam@nxp.com>, Ye Li <ye.li@nxp.com>,
"robh@kernel.org" <robh@kernel.org>,
"shawnguo@kernel.org" <shawnguo@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kernel@pengutronix.de" <kernel@pengutronix.de>
Subject: Re: [RESEND v2] soc: imx: Add generic i.MX8 SoC driver
Date: Thu, 28 Mar 2019 16:43:55 +0000 [thread overview]
Message-ID: <8df8afc4a50512d28247743e06f9ed30534da921.camel@nxp.com> (raw)
In-Reply-To: <1553273350-28852-1-git-send-email-abel.vesa@nxp.com>
On Fri, 2019-03-22 at 16:49 +0000, Abel Vesa wrote:
> Add generic i.MX8 SoC driver along with the i.MX8MQ SoC specific code.
> For now, only i.MX8MQ revision B1 is supported. For any other, i.MX8MQ
> revision it will print 'unknown'.
> +#define REV_B1 0x21
> +
> +#define IMX8MQ_SW_INFO_B1 0x40
> +#define IMX8MQ_SW_MAGIC_B1 0xff0055aa
> +
> + np = of_find_compatible_node(NULL, NULL, "fsl,imx8mq-ocotp");+
> + ocotp_base = of_iomap(np, 0);
> +
> + magic = readl_relaxed(ocotp_base + IMX8MQ_SW_INFO_B1);
> + if (magic == IMX8MQ_SW_MAGIC_B1)
> + rev = REV_B1;
This is based on ATF code in vendor tree, but shouldn't we have some
sort of explanation for this "magic"?
Looking at the OCOTP driver reg 0x40 is IMX_OCOTP_ADDR_DATA2 and it's
used as part of fuse writes. According to the driver code 8mq is
compatible with 7d and this write path is enabled for imx8mq-ocotp.
Looking at the OCOTP manual reg 0x40 is OCOTP_HW_OCOTP_READ_FUSE_DATA
and it's meant to be used together with IMX_OCOTP_ADDR_CTRL to read
info. Maybe my manual (rev0 2018-01) is incorrect?
Looking at the manual this will return the value of the fuse last
requested via IMX_OCOTP_ADDR_CTRL but no such request is made in this
driver. So reading from OCOTP 0x40 might return an unrelated value?!
The manual does document that fuse 0x440[3:0] is a "silicon revision
number"; maybe we should read that?
--
Regards,
Leonard
next prev parent reply other threads:[~2019-03-28 16:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-22 16:49 [RESEND v2] soc: imx: Add generic i.MX8 SoC driver Abel Vesa
2019-03-28 16:43 ` Leonard Crestez [this message]
2019-04-18 22:01 ` Leonard Crestez
2019-04-20 13:26 ` Shawn Guo
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