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Message-ID: <CAGS+omADXpnBnLvuH+xNmatL+89kLBELz6KqMFid7SOx=veiAg@mail.gmail.com>
Date: Fri, 15 May 2015 22:17:33 +0800
From: Daniel Kurtz <djkurtz@...omium.org>
To: Sascha Hauer <s.hauer@...gutronix.de>
Cc: "linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"open list:OPEN FIRMWARE AND..." <devicetree@...r.kernel.org>,
Kevin Hilman <khilman@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-mediatek@...ts.infradead.org,
Sasha Hauer <kernel@...gutronix.de>,
Matthias Brugger <matthias.bgg@...il.com>
Subject: Re: [PATCH 1/5] soc: mediatek: Add infracfg misc driver support
Hi Sascha,
On Tue, May 12, 2015 at 3:23 AM, Sascha Hauer <s.hauer@...gutronix.de> wrote:
> This adds support for some miscellaneous bits of the infracfg controller.
> The mtk_infracfg_set/clear_bus_protection functions are necessary for
> the scpsys power domain driver to handle the bus protection bits which
> are contained in the infacfg register space.
>
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> ---
> drivers/soc/mediatek/Kconfig | 9 +++++
> drivers/soc/mediatek/Makefile | 1 +
> drivers/soc/mediatek/mtk-infracfg.c | 80 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 90 insertions(+)
> create mode 100644 drivers/soc/mediatek/mtk-infracfg.c
>
> diff --git a/drivers/soc/mediatek/Kconfig b/drivers/soc/mediatek/Kconfig
> index bcdb22d..6fae66f 100644
> --- a/drivers/soc/mediatek/Kconfig
> +++ b/drivers/soc/mediatek/Kconfig
> @@ -9,3 +9,12 @@ config MTK_PMIC_WRAP
> Say yes here to add support for MediaTek PMIC Wrapper found
> on different MediaTek SoCs. The PMIC wrapper is a proprietary
> hardware to connect the PMIC.
> +
> +config MTK_INFRACFG
nit: Could you alphabetize these config options - so this one before
MTK_PMIC_WRAP
> + tristate "MediaTek INFRACFG Support"
> + depends on ARCH_MEDIATEK
I've seen several drivers like this now:
depends on ARCH_MEDIATEK || COMPILE_TEST
> + select REGMAP
> + help
> + Say yes here to add support for the MediaTek INFRACFG controller. The
> + INFRACFG controller contains various infrastructure registers not
> + directly associated to any device.
> diff --git a/drivers/soc/mediatek/Makefile b/drivers/soc/mediatek/Makefile
> index ecaf4de..ce39119 100644
> --- a/drivers/soc/mediatek/Makefile
> +++ b/drivers/soc/mediatek/Makefile
> @@ -1 +1,2 @@
> obj-$(CONFIG_MTK_PMIC_WRAP) += mtk-pmic-wrap.o
> +obj-$(CONFIG_MTK_INFRACFG) += mtk-infracfg.o
alphabetize here, too.
> diff --git a/drivers/soc/mediatek/mtk-infracfg.c b/drivers/soc/mediatek/mtk-infracfg.c
> new file mode 100644
> index 0000000..b3ebfae
> --- /dev/null
> +++ b/drivers/soc/mediatek/mtk-infracfg.c
> @@ -0,0 +1,80 @@
> +#include <linux/regmap.h>
> +#include <linux/export.h>
> +#include <linux/jiffies.h>
> +#include <linux/soc/mediatek/infracfg.h>
> +#include <asm/processor.h>
and... alphabetize headers here.
I'm not sure if people care, but I find it makes it much easier to
merge/add things later if these lists are already sorted.
Same "please alphabetize" comments for the mtk-scpsys patch, so I
won't repeat them.
> +
> +#define INFRA_TOPAXI_PROTECTEN 0x0220
> +#define INFRA_TOPAXI_PROTECTSTA1 0x0228
> +
> +/**
> + * mtk_infracfg_set_bus_protection - enable bus protection
> + * @regmap: The infracfg regmap
> + * @mask: The mask containing the protection bits to be enabled.
> + *
> + * This function enables the bus protection bits for disabled power
> + * domains so that the system does not hanf when some unit accesses the
> + * bus while in power down.
> + */
> +int mtk_infracfg_set_bus_protection(struct regmap *infracfg, u32 mask)
> +{
> + unsigned long expired;
> + u32 val;
> + int ret;
> +
> + regmap_update_bits(infracfg, INFRA_TOPAXI_PROTECTEN, mask, mask);
> +
> + expired = jiffies + HZ;
> +
> + while (1) {
> + ret = regmap_read(infracfg, INFRA_TOPAXI_PROTECTSTA1, &val);
> + if (ret)
> + return ret;
> +
> + if ((val & mask) == mask)
> + break;
> +
> + cpu_relax();
> + if (time_after(jiffies, expired))
> + return -EIO;
I think we should check for timeout first, and then cpu_relax() if
there is still time left (here and in
mtk_infracfg_clear_bus_protection()). Otherwise we end up doing one
final cpu_relax() without rechecking the register we are polling
(again, I have the same comment for the timeout loops in mtk-scpsys).
Also, shouldn't we return -ETIMEOUT if we timeout?
Thanks!
-Dan
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(mtk_infracfg_set_bus_protection);
> +
> +/**
> + * mtk_infracfg_clear_bus_protection - disable bus protection
> + * @regmap: The infracfg regmap
> + * @mask: The mask containing the protection bits to be disabled.
> + *
> + * This function disables the bus protection bits previously enabled with
> + * mtk_infracfg_set_bus_protection.
> + */
> +int mtk_infracfg_clear_bus_protection(struct regmap *infracfg, u32 mask)
> +{
> + unsigned long expired;
> + int ret;
> +
> + regmap_update_bits(infracfg, INFRA_TOPAXI_PROTECTEN, mask, 0);
> +
> + expired = jiffies + HZ;
> +
> + while (1) {
> + u32 val;
> +
> + ret = regmap_read(infracfg, INFRA_TOPAXI_PROTECTSTA1, &val);
> + if (ret)
> + return ret;
> +
> + if (!(val & mask))
> + break;
> +
> + cpu_relax();
> + if (time_after(jiffies, expired))
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(mtk_infracfg_clear_bus_protection);
> --
> 2.1.4
>
> --
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