From patchwork Thu Dec 3 09:53:50 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ludovic Desroches X-Patchwork-Id: 7757871 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id CDD869F39D for ; Thu, 3 Dec 2015 09:56:14 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DE9102054C for ; Thu, 3 Dec 2015 09:56:13 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E9AE720503 for ; Thu, 3 Dec 2015 09:56:12 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1a4QaU-0004yS-Os; Thu, 03 Dec 2015 09:54:06 +0000 Received: from eusmtp01.atmel.com ([212.144.249.242]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1a4QaK-0004qs-6r for linux-arm-kernel@lists.infradead.org; Thu, 03 Dec 2015 09:53:58 +0000 Received: from ibiza.corp.atmel.com (10.161.101.13) by eusmtp01.atmel.com (10.161.101.30) with Microsoft SMTP Server id 14.3.235.1; Thu, 3 Dec 2015 10:53:49 +0100 From: Ludovic Desroches To: , , Subject: [PATCH v2 1/4] i2c: at91: add support for the HOLD field Date: Thu, 3 Dec 2015 10:53:50 +0100 Message-ID: <1449136434-27619-2-git-send-email-ludovic.desroches@atmel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1449136434-27619-1-git-send-email-ludovic.desroches@atmel.com> References: <1449136434-27619-1-git-send-email-ludovic.desroches@atmel.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151203_015356_743740_E20913E5 X-CRM114-Status: GOOD ( 15.13 ) X-Spam-Score: -4.2 (----) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Ludovic Desroches , linux-i2c@vger.kernel.org, plagnioj@jcrosoft.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The hold field allows to configure the data hold time which can be set with the help of the generic binding 'i2c-sda-hold-time-ns'. This feature has been introduced with SAMA5D4 SoC family. Signed-off-by: Ludovic Desroches Acked-by: Nicolas Ferre --- drivers/i2c/busses/i2c-at91.c | 53 ++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 50 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c index 10835d1..921d32b 100644 --- a/drivers/i2c/busses/i2c-at91.c +++ b/drivers/i2c/busses/i2c-at91.c @@ -64,6 +64,8 @@ #define AT91_TWI_IADR 0x000c /* Internal Address Register */ #define AT91_TWI_CWGR 0x0010 /* Clock Waveform Generator Reg */ +#define AT91_TWI_CWGR_HOLD_MAX 0x1f +#define AT91_TWI_CWGR_HOLD(x) (((x) & AT91_TWI_CWGR_HOLD_MAX) << 24) #define AT91_TWI_SR 0x0020 /* Status Register */ #define AT91_TWI_TXCOMP BIT(0) /* Transmission Complete */ @@ -110,6 +112,7 @@ struct at91_twi_pdata { unsigned clk_offset; bool has_unre_flag; bool has_alt_cmd; + bool has_hold_field; struct at_dma_slave dma_slave; }; @@ -187,10 +190,11 @@ static void at91_init_twi_bus(struct at91_twi_dev *dev) */ static void at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk) { - int ckdiv, cdiv, div; + int ckdiv, cdiv, div, hold = 0; struct at91_twi_pdata *pdata = dev->pdata; int offset = pdata->clk_offset; int max_ckdiv = pdata->clk_max_div; + u32 twd_hold_time_ns = 0; div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk), 2 * twi_clk) - offset); @@ -204,8 +208,33 @@ static void at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk) cdiv = 255; } - dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv; - dev_dbg(dev->dev, "cdiv %d ckdiv %d\n", cdiv, ckdiv); + if (pdata->has_hold_field) { + of_property_read_u32(dev->dev->of_node, "i2c-sda-hold-time-ns", + &twd_hold_time_ns); + + /* + * hold time = HOLD + 3 x T_peripheral_clock + * Use clk rate in kHz to prevent overflows when computing + * hold. + */ + hold = DIV_ROUND_UP(twd_hold_time_ns + * (clk_get_rate(dev->clk) / 1000), 1000000); + hold -= 3; + if (hold < 0) + hold = 0; + if (hold > AT91_TWI_CWGR_HOLD_MAX) { + dev_warn(dev->dev, + "HOLD field set to its maximum value (%d instead of %d)\n", + AT91_TWI_CWGR_HOLD_MAX, hold); + hold = AT91_TWI_CWGR_HOLD_MAX; + } + } + + dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv + | AT91_TWI_CWGR_HOLD(hold); + + dev_dbg(dev->dev, "cdiv %d ckdiv %d hold %d (%d ns)\n", + cdiv, ckdiv, hold, twd_hold_time_ns); } static void at91_twi_dma_cleanup(struct at91_twi_dev *dev) @@ -797,6 +826,7 @@ static struct at91_twi_pdata at91rm9200_config = { .clk_offset = 3, .has_unre_flag = true, .has_alt_cmd = false, + .has_hold_field = false, }; static struct at91_twi_pdata at91sam9261_config = { @@ -804,6 +834,7 @@ static struct at91_twi_pdata at91sam9261_config = { .clk_offset = 4, .has_unre_flag = false, .has_alt_cmd = false, + .has_hold_field = false, }; static struct at91_twi_pdata at91sam9260_config = { @@ -811,6 +842,7 @@ static struct at91_twi_pdata at91sam9260_config = { .clk_offset = 4, .has_unre_flag = false, .has_alt_cmd = false, + .has_hold_field = false, }; static struct at91_twi_pdata at91sam9g20_config = { @@ -818,6 +850,7 @@ static struct at91_twi_pdata at91sam9g20_config = { .clk_offset = 4, .has_unre_flag = false, .has_alt_cmd = false, + .has_hold_field = false, }; static struct at91_twi_pdata at91sam9g10_config = { @@ -825,6 +858,7 @@ static struct at91_twi_pdata at91sam9g10_config = { .clk_offset = 4, .has_unre_flag = false, .has_alt_cmd = false, + .has_hold_field = false, }; static const struct platform_device_id at91_twi_devtypes[] = { @@ -854,6 +888,15 @@ static struct at91_twi_pdata at91sam9x5_config = { .clk_offset = 4, .has_unre_flag = false, .has_alt_cmd = false, + .has_hold_field = false, +}; + +static struct at91_twi_pdata sama5d4_config = { + .clk_max_div = 7, + .clk_offset = 4, + .has_unre_flag = false, + .has_alt_cmd = false, + .has_hold_field = true, }; static struct at91_twi_pdata sama5d2_config = { @@ -861,6 +904,7 @@ static struct at91_twi_pdata sama5d2_config = { .clk_offset = 4, .has_unre_flag = true, .has_alt_cmd = true, + .has_hold_field = true, }; static const struct of_device_id atmel_twi_dt_ids[] = { @@ -883,6 +927,9 @@ static const struct of_device_id atmel_twi_dt_ids[] = { .compatible = "atmel,at91sam9x5-i2c", .data = &at91sam9x5_config, }, { + .compatible = "atmel,sama5d4-i2c", + .data = &sama5d4_config, + }, { .compatible = "atmel,sama5d2-i2c", .data = &sama5d2_config, }, {