From patchwork Fri Aug 6 15:21:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sam Protsenko X-Patchwork-Id: 493556 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE906C432BE for ; Fri, 6 Aug 2021 15:22:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8EE4E611C9 for ; Fri, 6 Aug 2021 15:22:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244507AbhHFPWW (ORCPT ); Fri, 6 Aug 2021 11:22:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244503AbhHFPWQ (ORCPT ); Fri, 6 Aug 2021 11:22:16 -0400 Received: from mail-lj1-x230.google.com (mail-lj1-x230.google.com [IPv6:2a00:1450:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 064ABC0617A1 for ; Fri, 6 Aug 2021 08:21:56 -0700 (PDT) Received: by mail-lj1-x230.google.com with SMTP id h2so216160lji.6 for ; Fri, 06 Aug 2021 08:21:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=7149QsY3bxKHTBqGFladXmfU1OHnqAYwWvtju/kpgDw=; b=mU3tb0VOjIyfm2Q/1wxVB5IQeJY6SOfiPtxtSTAQSM7URQzOPL3Aj6JlwK9ogcH3sU SMRfbF3EFe3/V4/9h71BBGirdS9wb8TFJYrsXsbbkuV8Uiol9nOthlQtIBB3C+u0xHri 2Z917j9Wby2pjv5vyCqcjnIkOzxPZDgdZpHMDnwUTRYVWg8ENCrBT2mnatKNXyLzDTIs MTWCN8MC66Q6+dNxDk4R74/+PBJttkSfuGBh52UEQgGHiIgd+2GsCAO/TZjeJ9sXrw5w 0FBuR3pF8HVMuy85s7WKXXTLaKqIrxc9JsVbxi4yBObBekrmgOHh6gv0vNu76QiLGXOp A/VA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=7149QsY3bxKHTBqGFladXmfU1OHnqAYwWvtju/kpgDw=; b=AIyG4VEx0cJFr0BezJWltxwJWb1lZrrbW94lrmYYzd2IvrmaYhxtpWiyOCT7Jg7ZA3 nSngKhT8Vx0LA/ia8Hm5aPle9o4dLMXUyvyKi3zT1yqhXYNNNDJlAoZOP5Ex8pKKE6zg zitZq8Xo6Usuy2Uw5wxWrGppwZQJm4XxQudUVz9EY4Wt6bKRF6oq9QMP78fle5fBO/aQ wA9DSbTeTuGMVOM6v++KRepCz1tL3tzqyLe0MPXscmYmQ3o0hQAiWLqmoOekKEkAfJwP n0dFTlcXOcExFGjMKHclKXLb7l3mCwwDigUtVvcVAng0jcozpnlXyH57TYXekI9qIooe MT9A== X-Gm-Message-State: AOAM532zo87W/mjwjZcK7IhxYSHzUtvWN69+z4c9w+xyX3csgxdYOOP3 lPLg256NmB+587oixvqYoLYTRw== X-Google-Smtp-Source: ABdhPJz/nCSkupmdZvO+O/nPY21YE/Jn23nLsw919q8+GtfFLWrOy8Lwwb/7fmeR6+l9D649lgfGfQ== X-Received: by 2002:a2e:a887:: with SMTP id m7mr7083249ljq.236.1628263314373; Fri, 06 Aug 2021 08:21:54 -0700 (PDT) Received: from localhost ([31.134.121.151]) by smtp.gmail.com with ESMTPSA id u18sm87339ljj.2.2021.08.06.08.21.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Aug 2021 08:21:53 -0700 (PDT) From: Sam Protsenko To: Sylwester Nawrocki , Chanwoo Choi , Krzysztof Kozlowski , Linus Walleij , Tomasz Figa , =?utf-8?q?Pawe=C5=82_Chmiel?= Cc: Marc Zyngier , Rob Herring , Stephen Boyd , Michael Turquette , Jiri Slaby , Greg Kroah-Hartman , Charles Keepax , Ryu Euiyoul , Tom Gall , Sumit Semwal , John Stultz , Amit Pundir , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-serial@vger.kernel.org Subject: [PATCH v2 4/8] tty: serial: samsung: Init USI to keep clocks running Date: Fri, 6 Aug 2021 18:21:42 +0300 Message-Id: <20210806152146.16107-5-semen.protsenko@linaro.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210806152146.16107-1-semen.protsenko@linaro.org> References: <20210806152146.16107-1-semen.protsenko@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org UART block is a part of USI (Universal Serial Interface) IP-core in Samsung SoCs since Exynos9810 (e.g. in Exynos850). USI allows one to enable one of three types of serial interface: UART, SPI or I2C. That's possible because USI shares almost all internal circuits within each protocol. USI also provides some additional registers so it's possible to configure it. One USI register called USI_OPTION has reset value of 0x0. Because of this the clock gating behavior is controlled by hardware (HWACG = Hardware Auto Clock Gating), which simply means the serial won't work after reset as is. In order to make it work, USI_OPTION[2:1] bits must be set to 0b01, so that HWACG is controlled manually (by software). Bits meaning: - CLKREQ_ON = 1: clock is continuously provided to IP - CLKSTOP_ON = 0: drive IP_CLKREQ to High (needs to be set along with CLKREQ_ON = 1) USI is not present on older chips, like s3c2410, s3c2412, s3c2440, s3c6400, s5pv210, exynos5433, exynos4210. So the new boolean field '.has_usi' was added to struct s3c24xx_uart_info. USI registers will be only actually accessed when '.has_usi' field is set to "1". This feature is needed for further serial enablement on Exynos850, but some other new Exynos chips (like Exynos9810) may benefit from this feature as well. Signed-off-by: Sam Protsenko Reviewed-by: Krzysztof Kozlowski --- Changes in v2: - Non-intrusive modification of USI registers - Improved comments - Rearranged USI register definitions to conform with existing style drivers/tty/serial/samsung_tty.c | 32 +++++++++++++++++++++++++++++++- include/linux/serial_s3c.h | 9 +++++++++ 2 files changed, 40 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c index 9fbc61151c2e..b8034c1168e0 100644 --- a/drivers/tty/serial/samsung_tty.c +++ b/drivers/tty/serial/samsung_tty.c @@ -65,6 +65,7 @@ enum s3c24xx_port_type { struct s3c24xx_uart_info { char *name; enum s3c24xx_port_type type; + unsigned int has_usi; unsigned int port_type; unsigned int fifosize; unsigned long rx_fifomask; @@ -1352,6 +1353,28 @@ static int apple_s5l_serial_startup(struct uart_port *port) return ret; } +static void exynos_usi_init(struct uart_port *port) +{ + struct s3c24xx_uart_port *ourport = to_ourport(port); + struct s3c24xx_uart_info *info = ourport->info; + unsigned int val; + + if (!info->has_usi) + return; + + /* Clear the software reset of USI block (it's set at startup) */ + val = rd_regl(port, USI_CON); + val &= ~USI_CON_RESET_MASK; + wr_regl(port, USI_CON, val); + udelay(1); + + /* Continuously provide the clock to USI IP w/o gating (for Rx mode) */ + val = rd_regl(port, USI_OPTION); + val &= ~USI_OPTION_HWACG_MASK; + val |= USI_OPTION_HWACG_CLKREQ_ON; + wr_regl(port, USI_OPTION, val); +} + /* power power management control */ static void s3c24xx_serial_pm(struct uart_port *port, unsigned int level, @@ -1379,6 +1402,7 @@ static void s3c24xx_serial_pm(struct uart_port *port, unsigned int level, if (!IS_ERR(ourport->baudclk)) clk_prepare_enable(ourport->baudclk); + exynos_usi_init(port); break; default: dev_err(port->dev, "s3c24xx_serial: unknown pm %d\n", level); @@ -2102,6 +2126,8 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport, if (ret) pr_warn("uart: failed to enable baudclk\n"); + exynos_usi_init(port); + /* Keep all interrupts masked and cleared */ switch (ourport->info->type) { case TYPE_S3C6400: @@ -2750,10 +2776,11 @@ static struct s3c24xx_serial_drv_data s5pv210_serial_drv_data = { #endif #if defined(CONFIG_ARCH_EXYNOS) -#define EXYNOS_COMMON_SERIAL_DRV_DATA \ +#define EXYNOS_COMMON_SERIAL_DRV_DATA_USI(_has_usi) \ .info = &(struct s3c24xx_uart_info) { \ .name = "Samsung Exynos UART", \ .type = TYPE_S3C6400, \ + .has_usi = _has_usi, \ .port_type = PORT_S3C6400, \ .has_divslot = 1, \ .rx_fifomask = S5PV210_UFSTAT_RXMASK, \ @@ -2773,6 +2800,9 @@ static struct s3c24xx_serial_drv_data s5pv210_serial_drv_data = { .has_fracval = 1, \ } \ +#define EXYNOS_COMMON_SERIAL_DRV_DATA \ + EXYNOS_COMMON_SERIAL_DRV_DATA_USI(0) + static struct s3c24xx_serial_drv_data exynos4210_serial_drv_data = { EXYNOS_COMMON_SERIAL_DRV_DATA, .fifosize = { 256, 64, 16, 16 }, diff --git a/include/linux/serial_s3c.h b/include/linux/serial_s3c.h index f6c3323fc4c5..cf0de4a86640 100644 --- a/include/linux/serial_s3c.h +++ b/include/linux/serial_s3c.h @@ -27,6 +27,15 @@ #define S3C2410_UERSTAT (0x14) #define S3C2410_UFSTAT (0x18) #define S3C2410_UMSTAT (0x1C) +#define USI_CON (0xC4) +#define USI_OPTION (0xC8) + +#define USI_CON_RESET (1<<0) +#define USI_CON_RESET_MASK (1<<0) + +#define USI_OPTION_HWACG_CLKREQ_ON (1<<1) +#define USI_OPTION_HWACG_CLKSTOP_ON (1<<2) +#define USI_OPTION_HWACG_MASK (3<<1) #define S3C2410_LCON_CFGMASK ((0xF<<3)|(0x3))