From patchwork Thu Aug 15 21:41:31 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= X-Patchwork-Id: 1147857 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=kleine-koenig.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 468fzj442wz9s3Z for ; Fri, 16 Aug 2019 07:41:53 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726256AbfHOVlw (ORCPT ); Thu, 15 Aug 2019 17:41:52 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:35951 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732682AbfHOVlw (ORCPT ); Thu, 15 Aug 2019 17:41:52 -0400 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1hyNVA-0007cE-3U; Thu, 15 Aug 2019 23:41:44 +0200 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1hyNV8-0003Gl-Br; Thu, 15 Aug 2019 23:41:42 +0200 From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= To: Claudiu Beznea , Thierry Reding Cc: Nicolas Ferre , Alexandre Belloni , Ludovic Desroches , linux-arm-kernel@lists.infradead.org, linux-pwm@vger.kernel.org Subject: [PATCH 1/3] pwm: atmel: Add link to reference manual Date: Thu, 15 Aug 2019 23:41:31 +0200 Message-Id: <20190815214133.11134-1-uwe@kleine-koenig.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-pwm@vger.kernel.org Sender: linux-pwm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org The reference manual for at least one of the supported variants is publicly available. Add a link to it at the top of the driver. Signed-off-by: Uwe Kleine-König --- drivers/pwm/pwm-atmel.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c index e5e1eaf372fa..ac3d7a200b9e 100644 --- a/drivers/pwm/pwm-atmel.c +++ b/drivers/pwm/pwm-atmel.c @@ -4,6 +4,9 @@ * * Copyright (C) 2013 Atmel Corporation * Bo Shen + * + * Reference manual for "atmel,at91sam9rl-pwm": + * http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-11032-32-bit-ARM926EJ-S-Microcontroller-SAM9G25_Datasheet.pdf */ #include From patchwork Thu Aug 15 21:41:32 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= X-Patchwork-Id: 1147858 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=kleine-koenig.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 468fzk64kwz9sDQ for ; Fri, 16 Aug 2019 07:41:54 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732682AbfHOVlx (ORCPT ); Thu, 15 Aug 2019 17:41:53 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:56155 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728828AbfHOVlw (ORCPT ); Thu, 15 Aug 2019 17:41:52 -0400 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1hyNVA-0007cF-3T; Thu, 15 Aug 2019 23:41:44 +0200 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1hyNV8-0003Go-HM; Thu, 15 Aug 2019 23:41:42 +0200 From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= To: Claudiu Beznea , Thierry Reding Cc: Nicolas Ferre , Alexandre Belloni , Ludovic Desroches , linux-arm-kernel@lists.infradead.org, linux-pwm@vger.kernel.org Subject: [PATCH 2/3] pwm: atmel: use a constant for maximum prescale value Date: Thu, 15 Aug 2019 23:41:32 +0200 Message-Id: <20190815214133.11134-2-uwe@kleine-koenig.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190815214133.11134-1-uwe@kleine-koenig.org> References: <20190815214133.11134-1-uwe@kleine-koenig.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-pwm@vger.kernel.org Sender: linux-pwm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org The maximal prescale value is 10 for all supported variants. So drop the member in the variant description and introduce a global constant instead. This reduces the size of the variant descriptions and the .apply() callback can be compiled a bit more effectively. Signed-off-by: Uwe Kleine-König Acked-by: Claudiu Beznea --- drivers/pwm/pwm-atmel.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c index ac3d7a200b9e..d7a6d32b5774 100644 --- a/drivers/pwm/pwm-atmel.c +++ b/drivers/pwm/pwm-atmel.c @@ -50,6 +50,8 @@ #define PWMV2_CPRD 0x0C #define PWMV2_CPRDUPD 0x10 +#define PWM_MAX_PRES 10 + struct atmel_pwm_registers { u8 period; u8 period_upd; @@ -59,7 +61,6 @@ struct atmel_pwm_registers { struct atmel_pwm_config { u32 max_period; - u32 max_pres; }; struct atmel_pwm_data { @@ -126,7 +127,7 @@ static int atmel_pwm_calculate_cprd_and_pres(struct pwm_chip *chip, for (*pres = 0; cycles > atmel_pwm->data->cfg.max_period; cycles >>= 1) (*pres)++; - if (*pres > atmel_pwm->data->cfg.max_pres) { + if (*pres > PWM_MAX_PRES) { dev_err(chip->dev, "pres exceeds the maximum value\n"); return -EINVAL; } @@ -289,7 +290,6 @@ static const struct atmel_pwm_data atmel_sam9rl_pwm_data = { .cfg = { /* 16 bits to keep period and duty. */ .max_period = 0xffff, - .max_pres = 10, }, }; @@ -303,7 +303,6 @@ static const struct atmel_pwm_data atmel_sama5_pwm_data = { .cfg = { /* 16 bits to keep period and duty. */ .max_period = 0xffff, - .max_pres = 10, }, }; @@ -317,7 +316,6 @@ static const struct atmel_pwm_data mchp_sam9x60_pwm_data = { .cfg = { /* 32 bits to keep period and duty. */ .max_period = 0xffffffff, - .max_pres = 10, }, }; From patchwork Thu Aug 15 21:41:33 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= X-Patchwork-Id: 1147859 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=kleine-koenig.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 468fzm1rcZz9s3Z for ; Fri, 16 Aug 2019 07:41:56 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731991AbfHOVl4 (ORCPT ); Thu, 15 Aug 2019 17:41:56 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:35617 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728828AbfHOVlz (ORCPT ); Thu, 15 Aug 2019 17:41:55 -0400 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1hyNVA-0007cG-3U; Thu, 15 Aug 2019 23:41:44 +0200 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1hyNV8-0003Gr-M0; Thu, 15 Aug 2019 23:41:42 +0200 From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= To: Claudiu Beznea , Thierry Reding Cc: Nicolas Ferre , Alexandre Belloni , Ludovic Desroches , linux-arm-kernel@lists.infradead.org, linux-pwm@vger.kernel.org Subject: [PATCH 3/3] pwm: atmel: replace loop in prescale calculation by ad-hoc calculation Date: Thu, 15 Aug 2019 23:41:33 +0200 Message-Id: <20190815214133.11134-3-uwe@kleine-koenig.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190815214133.11134-1-uwe@kleine-koenig.org> References: <20190815214133.11134-1-uwe@kleine-koenig.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-pwm@vger.kernel.org Sender: linux-pwm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org The calculated values are the same with the modified algorithm. The only difference is that the calculation is a bit more efficient. Signed-off-by: Uwe Kleine-König Acked-by: Claudiu Beznea --- drivers/pwm/pwm-atmel.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c index d7a6d32b5774..42fe7bc043a8 100644 --- a/drivers/pwm/pwm-atmel.c +++ b/drivers/pwm/pwm-atmel.c @@ -60,7 +60,7 @@ struct atmel_pwm_registers { }; struct atmel_pwm_config { - u32 max_period; + u32 period_bits; }; struct atmel_pwm_data { @@ -119,17 +119,27 @@ static int atmel_pwm_calculate_cprd_and_pres(struct pwm_chip *chip, { struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); unsigned long long cycles = state->period; + int shift; /* Calculate the period cycles and prescale value */ cycles *= clk_get_rate(atmel_pwm->clk); do_div(cycles, NSEC_PER_SEC); - for (*pres = 0; cycles > atmel_pwm->data->cfg.max_period; cycles >>= 1) - (*pres)++; + /* + * The register for the period length is cfg.period_bits bits wide. + * So for each bit the number of clock cycles is wider divide the input + * clock frequency by two using pres and shift cprd accordingly. + */ + shift = fls(cycles) - atmel_pwm->data->cfg.period_bits; - if (*pres > PWM_MAX_PRES) { + if (shift > PWM_MAX_PRES) { dev_err(chip->dev, "pres exceeds the maximum value\n"); return -EINVAL; + } else if (shift > 0) { + *pres = shift; + cycles >>= *pres; + } else { + *pres = 0; } *cprd = cycles; @@ -289,7 +299,7 @@ static const struct atmel_pwm_data atmel_sam9rl_pwm_data = { }, .cfg = { /* 16 bits to keep period and duty. */ - .max_period = 0xffff, + .period_bits = 16, }, }; @@ -302,7 +312,7 @@ static const struct atmel_pwm_data atmel_sama5_pwm_data = { }, .cfg = { /* 16 bits to keep period and duty. */ - .max_period = 0xffff, + .period_bits = 16, }, }; @@ -315,7 +325,7 @@ static const struct atmel_pwm_data mchp_sam9x60_pwm_data = { }, .cfg = { /* 32 bits to keep period and duty. */ - .max_period = 0xffffffff, + .period_bits = 32, }, }; From patchwork Fri Aug 16 09:37:48 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= X-Patchwork-Id: 1148115 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=kleine-koenig.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 468yt91SSYz9sDQ for ; Fri, 16 Aug 2019 19:38:08 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726882AbfHPJiI (ORCPT ); Fri, 16 Aug 2019 05:38:08 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:50079 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726753AbfHPJiI (ORCPT ); Fri, 16 Aug 2019 05:38:08 -0400 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1hyYgI-0008M5-Oy; Fri, 16 Aug 2019 11:37:58 +0200 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1hyYgG-0003yW-Gx; Fri, 16 Aug 2019 11:37:56 +0200 From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= To: Claudiu Beznea , Thierry Reding Cc: Nicolas Ferre , Alexandre Belloni , Ludovic Desroches , linux-arm-kernel@lists.infradead.org, linux-pwm@vger.kernel.org Subject: [PATCH 4/3] pwm: atmel: document known weaknesses of both hardware and software Date: Fri, 16 Aug 2019 11:37:48 +0200 Message-Id: <20190816093748.11769-1-uwe@kleine-koenig.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190815214133.11134-1-uwe@kleine-koenig.org> References: <20190815214133.11134-1-uwe@kleine-koenig.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-pwm@vger.kernel.org Sender: linux-pwm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org Signed-off-by: Uwe Kleine-König --- drivers/pwm/pwm-atmel.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c index 42fe7bc043a8..1ddb93db9627 100644 --- a/drivers/pwm/pwm-atmel.c +++ b/drivers/pwm/pwm-atmel.c @@ -7,6 +7,16 @@ * * Reference manual for "atmel,at91sam9rl-pwm": * http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-11032-32-bit-ARM926EJ-S-Microcontroller-SAM9G25_Datasheet.pdf + * + * Limitations: + * - Periods start with the inactive level. + * - Hardware has to be stopped in general to update settings. + * + * Software bugs/possible improvements: + * - When atmel_pwm_apply() is called with state->enabled=false a change in + * state->polarity isn't honored. + * - Instead of sleeping to wait for a completed period, the interrupt + * functionality could be used. */ #include