From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 82FD7C27C53 for ; Wed, 19 Jun 2024 06:30:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=9b84qDZPpTsFo5d57CtSuEmMC3c74+6Nc/9EisxSUg8=; b=H1MUiuLQb/tTHAfpgLvAoveZej GmIJm0Kh5ID/YTPF62bEvLOuzrwK85QQ7Ttiv8flQKzQjSrQSGGvpHommeQklqu4d33VEr5cF2uBL fXJ/m1e94rWOxUK+lCztSQHZOSKYk8eEJxjGdl6stjVtnSSFM+TkOg/TdtqzIO1WA41pYsMgOHtb8 hUEk4/Lt1jKJwKbVDgfs547502Gqpz+F86y9KFamel9TFYx1e5AhM/EgY4bykPcJqBb8lH2aQw70r HaOnh21/B7mDbqeB6cA+pUyzOvO2CkM/LzkyERDOmI/A/tkzZoaccHLsogdzUg6Yqd5oJAQ6VbXTt 8j4yaGWw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sJopN-000000003c5-2aeL; Wed, 19 Jun 2024 06:29:53 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sJopK-000000003af-3OSl for linux-arm-kernel@lists.infradead.org; Wed, 19 Jun 2024 06:29:52 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id D717061989; Wed, 19 Jun 2024 06:29:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74BA4C2BBFC; Wed, 19 Jun 2024 06:29:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718778588; bh=qrqiVK2ovLgHbXt6I0KvbL8dDMz2xJDacD99Uke7Uns=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=QHkweQTOdM+YxrEh+N40f+mW6QOCe++11SQvXe1W/zyPJ7UfRiIhK6d6Ce6HYELBz qVj5z8PtIOEsky5HlXbZG88p2vF4y0JULV3LJK/2uH43fmwLc5btA5uynh9NU5YhR4 xyrUDRPfFItFpStjAvNiJG6v7BZ+9v5detpc3ogmcXRLRob88e6TZ8o+Hjgq1KOHBp c3hyjnKe9qZFwRlOj+g2qsU0zLSDjSpJRkqe30iu2PFar1O3OyGHJ7VHQfxm7N0URI Xd/cWLkVyW6ZvO2zh09v7e82eyq13olvKxSVJb7o7Fy+FMwTNaJWbz9eXBHX1kbUj1 /hhdIo8OmNbSg== Message-ID: Date: Wed, 19 Jun 2024 08:29:42 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mfd: syscon: add of_syscon_register_regmap() API To: Peter Griffin , lee@kernel.org, arnd@arndb.de, alim.akhtar@samsung.com Cc: linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, tudor.ambarus@linaro.org, andre.draszik@linaro.org, saravanak@google.com, willmcvicker@google.com, semen.protsenko@linaro.org, kernel-team@android.com References: <20240614140421.3172674-1-peter.griffin@linaro.org> <20240614140421.3172674-2-peter.griffin@linaro.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240618_232951_018163_98CB5438 X-CRM114-Status: GOOD ( 27.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 14/06/2024 16:04, Peter Griffin wrote: > The of_syscon_register_regmap() API allows an externally created regmap > to be registered with syscon. This regmap can then be returned to client > drivers using the syscon_regmap_lookup_by_phandle() APIs. > > The API is used by platforms where mmio access to the syscon registers is > not possible, and a underlying soc driver like exynos-pmu provides a SoC > specific regmap that can issue a SMC or hypervisor call to write the > register. > > This approach keeps the SoC complexities out of syscon, but allows common > drivers such as syscon-poweroff, syscon-reboot and friends that are used > by many SoCs already to be re-used. > > Signed-off-by: Peter Griffin > --- > drivers/mfd/syscon.c | 48 ++++++++++++++++++++++++++++++++++++++ > include/linux/mfd/syscon.h | 8 +++++++ > 2 files changed, 56 insertions(+) > > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c > index 7d0e91164cba..44991da3ea23 100644 > --- a/drivers/mfd/syscon.c > +++ b/drivers/mfd/syscon.c > @@ -192,6 +192,54 @@ static struct regmap *device_node_get_regmap(struct device_node *np, > return syscon->regmap; > } > > +/** > + * of_syscon_register_regmap() - Register regmap for specified device node > + * @np: Device tree node > + * @regmap: Pointer to regmap object > + * > + * Register an externally created regmap object with syscon for the specified > + * device tree node. This regmap can then be returned to client drivers using > + * the syscon_regmap_lookup_by_phandle() API. > + * > + * Return: 0 on success, negative error code on failure. > + */ > +int of_syscon_register_regmap(struct device_node *np, struct regmap *regmap) > +{ > + struct syscon *entry, *syscon = NULL; > + > + if (!np || !regmap) > + return -EINVAL; > + > + /* check if syscon entry already exists */ > + spin_lock(&syscon_list_slock); > + > + list_for_each_entry(entry, &syscon_list, list) > + if (entry->np == np) { > + syscon = entry; > + break; > + } > + > + spin_unlock(&syscon_list_slock); > + > + if (syscon) > + return -EEXIST; > + > + syscon = kzalloc(sizeof(*syscon), GFP_KERNEL); > + if (!syscon) > + return -ENOMEM; > + > + syscon->regmap = regmap; > + syscon->np = np; > + > + /* register the regmap in syscon list */ > + spin_lock(&syscon_list_slock); You still have window between the check for existing syscon and adding to the list. This likely is not an issue now, but it might if we have more devices using same syscon and we enable asynchronous probing. > + list_add_tail(&syscon->list, &syscon_list); > + spin_unlock(&syscon_list_slock); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(of_syscon_register_regmap); > + Best regards, Krzysztof