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([2003:62:5f1b:3000:8dbc:eb8a:fb9c:9173]) by smtp.googlemail.com with ESMTPSA id xb6sm29216252wjb.30.2016.10.02.05.24.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 02 Oct 2016 05:24:24 -0700 (PDT) From: Heiner Kallweit Subject: [PATCH 10/11] spi: fsl-espi: add support for RXSKIP mode To: Mark Brown References: <5b98be38-17a2-79a2-14da-fb2bb6f8820f@gmail.com> Cc: "linux-spi@vger.kernel.org" Message-ID: Date: Sun, 2 Oct 2016 14:23:51 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <5b98be38-17a2-79a2-14da-fb2bb6f8820f@gmail.com> Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch adds support for ESPI RXSKIP mode. This mode is optimized for flash reads: - sends a number of bytes and then reads a number of bytes - shifts out zeros automatically when reading - optionally can be configured for dual read mode Signed-off-by: Heiner Kallweit --- drivers/spi/spi-fsl-espi.c | 56 ++++++++++++++++++++++++++++++++++++++++++---- drivers/spi/spi-fsl-lib.h | 1 + 2 files changed, 53 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c index cbfb6da..8cfcf41 100644 --- a/drivers/spi/spi-fsl-espi.c +++ b/drivers/spi/spi-fsl-espi.c @@ -150,7 +150,8 @@ static void fsl_espi_copy_to_buf(struct spi_message *m, list_for_each_entry(t, &m->transfers, transfer_list) { if (t->tx_buf) fsl_espi_memcpy_swab(buf, t->tx_buf, m, t); - else + /* In RXSKIP mode controller shifts zeros automatically */ + else if (!mspi->rxskip) memset(buf, 0, t->len); buf += t->len; } @@ -203,6 +204,42 @@ static int fsl_espi_check_message(struct spi_message *m) return 0; } +static void fsl_espi_check_rxskip_mode(struct spi_message *m, + struct mpc8xxx_spi *mspi) +{ + struct spi_transfer *t; + unsigned int i = 0, rxskip_len = 0; + + mspi->rxskip = 0; + + /* + * prerequisites for rxskip mode: + * - message has two transfers + * - first transfer is a write and second is a read + * + * In addition enable rxskip mode only if length of write transfer + * is <= FSL_ESPI_FIFO_SIZE. This allows to keep the current + * low-level transfer implementation. + * This constraint doesn't affect SPI NOR reads as typical use case + * for rxskip mode as the read command has only few bytes. + */ + list_for_each_entry(t, &m->transfers, transfer_list) { + if (i == 0) { + if (!t->tx_buf || t->rx_buf || + t->len > FSL_ESPI_FIFO_SIZE) + return; + rxskip_len = t->len; + } else if (i == 1) { + if (t->tx_buf || !t->rx_buf) + return; + } + i++; + } + + if (i == 2) + mspi->rxskip = rxskip_len; +} + static void fsl_espi_fill_tx_fifo(struct mpc8xxx_spi *mspi, u32 events) { u32 tx_fifo_avail; @@ -282,7 +319,7 @@ static void fsl_espi_setup_transfer(struct spi_device *spi, static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t) { struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(spi->master); - u32 mask; + u32 mask, spcom; int ret; mpc8xxx_spi->rx_len = t->len; @@ -294,8 +331,18 @@ static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t) reinit_completion(&mpc8xxx_spi->done); /* Set SPCOM[CS] and SPCOM[TRANLEN] field */ - fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPCOM, - (SPCOM_CS(spi->chip_select) | SPCOM_TRANLEN(t->len - 1))); + spcom = SPCOM_CS(spi->chip_select); + spcom |= SPCOM_TRANLEN(t->len - 1); + + /* configure RXSKIP mode */ + if (mpc8xxx_spi->rxskip) { + spcom |= SPCOM_RXSKIP(mpc8xxx_spi->rxskip); + mpc8xxx_spi->tx_len = mpc8xxx_spi->rxskip; + mpc8xxx_spi->rx_len = t->len - mpc8xxx_spi->rxskip; + mpc8xxx_spi->rx = t->rx_buf + mpc8xxx_spi->rxskip; + } + + fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPCOM, spcom); /* enable interrupts */ mask = SPIM_DON; @@ -327,6 +374,7 @@ static int fsl_espi_trans(struct spi_message *m, struct spi_transfer *trans) struct spi_device *spi = m->spi; int ret; + fsl_espi_check_rxskip_mode(m, mspi); fsl_espi_copy_to_buf(m, mspi); fsl_espi_setup_transfer(spi, trans); diff --git a/drivers/spi/spi-fsl-lib.h b/drivers/spi/spi-fsl-lib.h index 35a7a17..8096fae 100644 --- a/drivers/spi/spi-fsl-lib.h +++ b/drivers/spi/spi-fsl-lib.h @@ -32,6 +32,7 @@ struct mpc8xxx_spi { unsigned int rx_len; unsigned int tx_len; u8 *local_buf; + unsigned int rxskip; spinlock_t lock; #endif