From patchwork Wed Aug 11 11:48:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sam Protsenko X-Patchwork-Id: 496293 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 D6F2EC4338F for ; Wed, 11 Aug 2021 11:48:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BEDDD60F55 for ; Wed, 11 Aug 2021 11:48:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237490AbhHKLtK (ORCPT ); Wed, 11 Aug 2021 07:49:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237479AbhHKLtC (ORCPT ); Wed, 11 Aug 2021 07:49:02 -0400 Received: from mail-ed1-x529.google.com (mail-ed1-x529.google.com [IPv6:2a00:1450:4864:20::529]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC593C0617BC for ; Wed, 11 Aug 2021 04:48:36 -0700 (PDT) Received: by mail-ed1-x529.google.com with SMTP id y7so3301750eda.5 for ; Wed, 11 Aug 2021 04:48:36 -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=15yds4+NLfeqfOc0EF0N+t+Hv6YtwmRG2QxE75vv5f4=; b=jkT2rtkVdgasC3tyUdbd1tbCUdx1RXHtzUZCBPcFXGcEhf01ZOFnIE64UnipIiTcGX HmvG4YBN471wXSAr7KMLL6y3FRFITbu9a/4wtR6lH4TjD1gOMtKTUYBnx/6rf+EGf7dg NPmMG7y6OYLFI5EJ7akmZFxrETNN3iS5kggvrhGkRu8Or0rmkJNcePCsjBRzAmvs2UnO 9doFEhD/rhaFRN8fgZClAR0lyN3P6HjU8hv9+J85OlXxJS6iA87zat9gyDyck7tsQIFG MYHeDd6cy612qvZ9roWnjodApngSXIsxAkCdSi2LtZrRZKykdtler30kTS3X4zqUzLhX CI4w== 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=15yds4+NLfeqfOc0EF0N+t+Hv6YtwmRG2QxE75vv5f4=; b=pvR9jiqKjezFayTGdFH6w+7TiujALzE1lmirjooTIYCV+Bakk4ODlKLGTsvZHyfIIt E1vfe4g0ObbOsjNnTS0hCvLFE8XfBa6yC+iLr2VI3AMJAHG8ffMqqiYxObXnkOnrpD4R DRMMD4seElSAzurAxfBdph/798MOH8y9GCabK9o5plaImbAMjpKJX1bb9QI0dZOvRc6I SupHqBCdL44YrmLPo8pO3YmzYGJLSUypFrUwgOGYqfhUwxSyYk58z3BVHJPxgoRJjBKI ih70SjPf2LZNo16JakwdJwk+LwZPTU7x0Q8lpd4WHiDln27ElGdCu36AYlrgXOE/n128 3t1w== X-Gm-Message-State: AOAM531T6/KcY0RJevcYt9DAHxMg7AcpaOKLmrNrE456JW0WcKlffMe+ UWmSoFcjGXnjRe9lHKPYGgiwtg== X-Google-Smtp-Source: ABdhPJz038sdr1rjjB+o6/m46kT4f9qSZlZKsdZbtj+suCBUP0Gd7koAM0sf8tb6RJqbzGSWWiY7fw== X-Received: by 2002:aa7:de14:: with SMTP id h20mr10761170edv.43.1628682515357; Wed, 11 Aug 2021 04:48:35 -0700 (PDT) Received: from localhost ([31.134.121.151]) by smtp.gmail.com with ESMTPSA id r2sm6705051edv.78.2021.08.11.04.48.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Aug 2021 04:48:34 -0700 (PDT) From: Sam Protsenko To: Krzysztof Kozlowski , Sylwester Nawrocki , =?utf-8?q?Pawe=C5=82_Chmiel?= , Chanwoo Choi Cc: Linus Walleij , Tomasz Figa , 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-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-serial@vger.kernel.org Subject: [PATCH v3 4/7] tty: serial: samsung: Init USI to keep clocks running Date: Wed, 11 Aug 2021 14:48:24 +0300 Message-Id: <20210811114827.27322-5-semen.protsenko@linaro.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210811114827.27322-1-semen.protsenko@linaro.org> References: <20210811114827.27322-1-semen.protsenko@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-gpio@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. Reviewed-by: Krzysztof Kozlowski Signed-off-by: Sam Protsenko --- Changes in v3: - Added Reviewed-by tag by Krzysztof 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))