From patchwork Wed Oct 7 23:55:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Semin X-Patchwork-Id: 11821967 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1029E139F for ; Wed, 7 Oct 2020 23:56:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFB0B206FC for ; Wed, 7 Oct 2020 23:56:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728560AbgJGX4Q (ORCPT ); Wed, 7 Oct 2020 19:56:16 -0400 Received: from mail.baikalelectronics.com ([87.245.175.226]:45790 "EHLO mail.baikalelectronics.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728969AbgJGXzl (ORCPT ); Wed, 7 Oct 2020 19:55:41 -0400 Received: from localhost (unknown [127.0.0.1]) by mail.baikalelectronics.ru (Postfix) with ESMTP id E588B803016F; Wed, 7 Oct 2020 23:55:29 +0000 (UTC) X-Virus-Scanned: amavisd-new at baikalelectronics.ru Received: from mail.baikalelectronics.ru ([127.0.0.1]) by localhost (mail.baikalelectronics.ru [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id c9Jpki4uTo31; Thu, 8 Oct 2020 02:55:29 +0300 (MSK) From: Serge Semin To: Mark Brown , Serge Semin CC: Serge Semin , Alexey Malahov , Ramil Zaripov , Pavel Parkhomenko , Andy Shevchenko , Andy Shevchenko , Lars Povlsen , "wuxu . wu" , Feng Tang , Rob Herring , , , Subject: [PATCH v4 19/21] spi: dw: Add poll-based SPI transfers support Date: Thu, 8 Oct 2020 02:55:08 +0300 Message-ID: <20201007235511.4935-20-Sergey.Semin@baikalelectronics.ru> In-Reply-To: <20201007235511.4935-1-Sergey.Semin@baikalelectronics.ru> References: <20201007235511.4935-1-Sergey.Semin@baikalelectronics.ru> MIME-Version: 1.0 X-ClientProxiedBy: MAIL.baikal.int (192.168.51.25) To mail (192.168.51.25) Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org A functionality of the poll-based transfer has been removed by commit 1ceb09717e98 ("spi: dw: remove cs_control and poll_mode members from chip_data") with a justification that "there is no user of one anymore". It turns out one of our DW APB SSI core is synthesized with no IRQ line attached and the only possible way of using it is to implement a poll-based SPI transfer procedure. So we have to get the removed functionality back, but with some alterations described below. First of all the poll-based transfer is activated only if the DW SPI controller doesn't have an IRQ line attached and the Linux IRQ number is initialized with the IRQ_NOTCONNECTED value. Secondly the transfer procedure is now executed with a delay performed between writer and reader methods. The delay value is calculated based on the number of data words expected to be received on the current iteration. Finally the errors status is checked on each iteration. Signed-off-by: Serge Semin --- drivers/spi/spi-dw-core.c | 40 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c index bcfa224e0e43..2e50cc0a9291 100644 --- a/drivers/spi/spi-dw-core.c +++ b/drivers/spi/spi-dw-core.c @@ -364,6 +364,42 @@ static void dw_spi_irq_setup(struct dw_spi *dws) dws->transfer_handler = dw_spi_transfer_handler; } +/* + * The iterative procedure of the poll-based transfer is simple: write as much + * as possible to the Tx FIFO, wait until the pending to receive data is ready + * to be read, read it from the Rx FIFO and check whether the performed + * procedure has been successful. + * + * Note this method the same way as the IRQ-based transfer won't work well for + * the SPI devices connected to the controller with native CS due to the + * automatic CS assertion/de-assertion. + */ +static int dw_spi_poll_transfer(struct dw_spi *dws, + struct spi_transfer *transfer) +{ + struct spi_delay delay; + u16 nbits; + int ret; + + delay.unit = SPI_DELAY_UNIT_SCK; + nbits = dws->n_bytes * BITS_PER_BYTE; + + do { + dw_writer(dws); + + delay.value = nbits * (dws->rx_len - dws->tx_len); + spi_delay_exec(&delay, transfer); + + dw_reader(dws); + + ret = dw_spi_check_status(dws, true); + if (ret) + return ret; + } while (dws->rx_len); + + return 0; +} + static int dw_spi_transfer_one(struct spi_controller *master, struct spi_device *spi, struct spi_transfer *transfer) { @@ -408,6 +444,8 @@ static int dw_spi_transfer_one(struct spi_controller *master, if (dws->dma_mapped) return dws->dma_ops->dma_transfer(dws, transfer); + else if (dws->irq == IRQ_NOTCONNECTED) + return dw_spi_poll_transfer(dws, transfer); dw_spi_irq_setup(dws); @@ -817,7 +855,7 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws) ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev), master); - if (ret < 0) { + if (ret < 0 && ret != -ENOTCONN) { dev_err(dev, "can not get IRQ\n"); goto err_free_master; }