linux-kernel - Re: [PATCH 2/3] usb: chipidea: Add chipidea revision information

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Message-ID: <e7c92089fe1938c9f7f97bde12c6d8bc@agner.ch>
Date:	Wed, 24 Dec 2014 17:22:44 +0100
From:	Stefan Agner <stefan@...er.ch>
To:	Sanchayan Maity <maitysanchayan@...il.com>
Cc:	Peter.Chen@...escale.com, gregkh@...uxfoundation.org,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] usb: chipidea: Add chipidea revision information

On 2014-12-19 10:55, Sanchayan Maity wrote:
> Define ci_get_revision API to know the controller revision
> information according to chipidea 1.1a, 2.0a, 2.4 and 2.5a
> spec. Besides, add one entry in struct ci_hdrc to indicate
> revision information. This can be used for adding different
> code for revisions, implementing erratas.
> 
> Signed-off-by: Sanchayan Maity <maitysanchayan@...il.com>
> ---
>  drivers/usb/chipidea/bits.h |   10 ++++++++++
>  drivers/usb/chipidea/core.c |   23 +++++++++++++++++++++--
>  2 files changed, 31 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/chipidea/bits.h b/drivers/usb/chipidea/bits.h
> index ca57e3d..e935ccc 100644
> --- a/drivers/usb/chipidea/bits.h
> +++ b/drivers/usb/chipidea/bits.h
> @@ -15,6 +15,16 @@
>  
>  #include <linux/usb/ehci_def.h>
>  
> +/*
> + * ID
> + * For 1.x revision, bit24 - bit31 are reserved
> + * For 2.x revision, bit25 - bit28 are 0x2
> + */
> +#define TAG			(0x1F << 16)
> +#define REVISION		(0xF << 21)
> +#define VERSION			(0xF << 25)
> +#define CIVERSION		(0x7 << 29)
> +

Hm, the other defines use spaces in this file, I like tabs more too, but
I guess uniformity wins here.. Peter?

>  /* HCCPARAMS */
>  #define HCCPARAMS_LEN         BIT(17)
>  
> diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
> index 9bdc6bd..33a8c4a 100644
> --- a/drivers/usb/chipidea/core.c
> +++ b/drivers/usb/chipidea/core.c
> @@ -136,6 +136,22 @@ static int hw_alloc_regmap(struct ci_hdrc *ci, bool is_lpm)
>  	return 0;
>  }
>  
> +static enum CI_REVISION ci_get_revision(struct ci_hdrc *ci)
> +{
> +	int ver = hw_read_id_reg(ci, ID_ID, VERSION) >> __ffs(VERSION);
> +	enum CI_REVISION rev = CI_REVISION_UNKNOWN;
> +
> +	if (ver == 0x2) {
> +		int rev_reg = hw_read_id_reg
> +			(ci, ID_ID, REVISION) >> __ffs(REVISION);

This line break is somewhat awkward, doesn't help for good readability.

Is the local integer variable necessary at all? Enums are arithmetic
types, so afaik this should be fine too:
		rev = CI_REVISION_20;
		rev += hw_read_id_reg(ci, ID_ID, REVISION) >> __ffs(REVISION);

> +		rev = rev_reg + CI_REVISION_20;
> +	} else if (ver == 0x0) {
> +		rev = CI_REVISION_1X;
> +	}
> +
> +	return rev;
> +}
> +
>  /**
>   * hw_read_intr_enable: returns interrupt enable register
>   *
> @@ -245,8 +261,11 @@ static int hw_device_init(struct ci_hdrc *ci,
> void __iomem *base)
>  	/* Clear all interrupts status bits*/
>  	hw_write(ci, OP_USBSTS, 0xffffffff, 0xffffffff);
>  
> -	dev_dbg(ci->dev, "ChipIdea HDRC found, lpm: %d; cap: %p op: %p\n",
> -		ci->hw_bank.lpm, ci->hw_bank.cap, ci->hw_bank.op);
> +	ci->rev = ci_get_revision(ci);
> +
> +	dev_dbg(ci->dev,
> +		"ChipIdea HDRC found, revision: %d, lpm: %d; cap: %p op: %p\n",
> +		ci->rev, ci->hw_bank.lpm, ci->hw_bank.cap, ci->hw_bank.op);
>  
>  	/* setup lock mode ? */

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