From 67bb37c05a6b56e0e1f804706145a52f655af3f1 Mon Sep 17 00:00:00 2001 From: Louis Chauvet Date: Wed, 27 Mar 2024 09:43:36 +0100 Subject: [PATCH 1/3] spi: spi-omap2-mcspi.c: revert "Toggle CS after each word" Commit 5cbc7ca987fb ("spi: spi-omap2-mcspi.c: Toggle CS after each word") introduced the toggling of CS after each word for the omap2-mcspi controller. The implementation is not respectful of the actual spi_message content, so the CS can be raised after each word even if the transfer structure asks to keep the CS active for the whole operation. As it is not used anyway in the current Linux tree, it can be safely removed. Signed-off-by: Louis Chauvet Link: https://msgid.link/r/20240327-spi-omap2-mcspi-multi-mode-v3-1-c4ac329dd5a2@bootlin.com Signed-off-by: Mark Brown --- drivers/spi/spi-omap2-mcspi.c | 15 --------------- include/linux/platform_data/spi-omap2-mcspi.h | 3 --- 2 files changed, 18 deletions(-) diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c index ddf1c684bcc7..601acec37eca 100644 --- a/drivers/spi/spi-omap2-mcspi.c +++ b/drivers/spi/spi-omap2-mcspi.c @@ -1175,13 +1175,6 @@ static int omap2_mcspi_transfer_one(struct spi_controller *ctlr, t->bits_per_word == spi->bits_per_word) par_override = 0; } - if (cd && cd->cs_per_word) { - chconf = mcspi->ctx.modulctrl; - chconf &= ~OMAP2_MCSPI_MODULCTRL_SINGLE; - mcspi_write_reg(ctlr, OMAP2_MCSPI_MODULCTRL, chconf); - mcspi->ctx.modulctrl = - mcspi_read_cs_reg(spi, OMAP2_MCSPI_MODULCTRL); - } chconf = mcspi_cached_chconf0(spi); chconf &= ~OMAP2_MCSPI_CHCONF_TRM_MASK; @@ -1240,14 +1233,6 @@ out: status = omap2_mcspi_setup_transfer(spi, NULL); } - if (cd && cd->cs_per_word) { - chconf = mcspi->ctx.modulctrl; - chconf |= OMAP2_MCSPI_MODULCTRL_SINGLE; - mcspi_write_reg(ctlr, OMAP2_MCSPI_MODULCTRL, chconf); - mcspi->ctx.modulctrl = - mcspi_read_cs_reg(spi, OMAP2_MCSPI_MODULCTRL); - } - omap2_mcspi_set_enable(spi, 0); if (spi_get_csgpiod(spi, 0)) diff --git a/include/linux/platform_data/spi-omap2-mcspi.h b/include/linux/platform_data/spi-omap2-mcspi.h index 3b400b1919a9..9e3c15b4ac91 100644 --- a/include/linux/platform_data/spi-omap2-mcspi.h +++ b/include/linux/platform_data/spi-omap2-mcspi.h @@ -16,9 +16,6 @@ struct omap2_mcspi_platform_config { struct omap2_mcspi_device_config { unsigned turbo_mode:1; - - /* toggle chip select after every word */ - unsigned cs_per_word:1; }; #endif From d153ff4056cb346fd6182a8a1bea6e12b714b64f Mon Sep 17 00:00:00 2001 From: Louis Chauvet Date: Wed, 27 Mar 2024 09:43:37 +0100 Subject: [PATCH 2/3] spi: omap2-mcspi: Add support for MULTI-mode Introduce support for MULTI-mode in the OMAP2 MCSPI driver. Currently, the driver always uses SINGLE mode to handle the chip select (CS). With this enhancement, MULTI-mode is enabled for specific messages, allowing for a shorter delay between CS enable and the message (some FPGA devices are sensitive to this delay). The OMAP2 MCSPI device can use two different mode to send messages, SINGLE and MULTI: In SINGLE mode, the controller only leverages one single FIFO, and the host system has to manually select the CS it wants to enable. In MULTI mode, each CS is bound to a FIFO, the host system then writes the data to the relevant FIFO, as the hardware will take care of the CS The drawback of multi-mode is that it's not possible to keep the CS enabled between each words. Therefore, this patch enables multi-mode only for specific messages: the spi_message must contain only spi_transfer of 1 word (of any size) with cs_change enabled. A new member is introduced in the omap2_mcspi structure to keep track of the current used mode. Signed-off-by: Louis Chauvet Link: https://msgid.link/r/20240327-spi-omap2-mcspi-multi-mode-v3-2-c4ac329dd5a2@bootlin.com Signed-off-by: Mark Brown --- drivers/spi/spi-omap2-mcspi.c | 67 +++++++++++++++++++++++++++++++---- 1 file changed, 61 insertions(+), 6 deletions(-) diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c index 601acec37eca..002f29dbcea6 100644 --- a/drivers/spi/spi-omap2-mcspi.c +++ b/drivers/spi/spi-omap2-mcspi.c @@ -131,6 +131,7 @@ struct omap2_mcspi { unsigned int pin_dir:1; size_t max_xfer_len; u32 ref_clk_hz; + bool use_multi_mode; }; struct omap2_mcspi_cs { @@ -256,10 +257,15 @@ static void omap2_mcspi_set_cs(struct spi_device *spi, bool enable) l = mcspi_cached_chconf0(spi); - if (enable) + /* Only enable chip select manually if single mode is used */ + if (mcspi->use_multi_mode) { l &= ~OMAP2_MCSPI_CHCONF_FORCE; - else - l |= OMAP2_MCSPI_CHCONF_FORCE; + } else { + if (enable) + l &= ~OMAP2_MCSPI_CHCONF_FORCE; + else + l |= OMAP2_MCSPI_CHCONF_FORCE; + } mcspi_write_chconf0(spi, l); @@ -283,7 +289,12 @@ static void omap2_mcspi_set_mode(struct spi_controller *ctlr) l |= (OMAP2_MCSPI_MODULCTRL_MS); } else { l &= ~(OMAP2_MCSPI_MODULCTRL_MS); - l |= OMAP2_MCSPI_MODULCTRL_SINGLE; + + /* Enable single mode if needed */ + if (mcspi->use_multi_mode) + l &= ~OMAP2_MCSPI_MODULCTRL_SINGLE; + else + l |= OMAP2_MCSPI_MODULCTRL_SINGLE; } mcspi_write_reg(ctlr, OMAP2_MCSPI_MODULCTRL, l); @@ -1250,15 +1261,59 @@ static int omap2_mcspi_prepare_message(struct spi_controller *ctlr, struct omap2_mcspi *mcspi = spi_controller_get_devdata(ctlr); struct omap2_mcspi_regs *ctx = &mcspi->ctx; struct omap2_mcspi_cs *cs; + struct spi_transfer *tr; + u8 bits_per_word; - /* Only a single channel can have the FORCE bit enabled + /* + * The conditions are strict, it is mandatory to check each transfer of the list to see if + * multi-mode is applicable. + */ + mcspi->use_multi_mode = true; + list_for_each_entry(tr, &msg->transfers, transfer_list) { + if (!tr->bits_per_word) + bits_per_word = msg->spi->bits_per_word; + else + bits_per_word = tr->bits_per_word; + + /* + * Check if this transfer contains only one word; + */ + if (bits_per_word < 8 && tr->len == 1) { + /* multi-mode is applicable, only one word (1..7 bits) */ + } else if (bits_per_word >= 8 && tr->len == bits_per_word / 8) { + /* multi-mode is applicable, only one word (8..32 bits) */ + } else { + /* multi-mode is not applicable: more than one word in the transfer */ + mcspi->use_multi_mode = false; + } + + /* Check if transfer asks to change the CS status after the transfer */ + if (!tr->cs_change) + mcspi->use_multi_mode = false; + + /* + * If at least one message is not compatible, switch back to single mode + * + * The bits_per_word of certain transfer can be different, but it will have no + * impact on the signal itself. + */ + if (!mcspi->use_multi_mode) + break; + } + + omap2_mcspi_set_mode(ctlr); + + /* In single mode only a single channel can have the FORCE bit enabled * in its chconf0 register. * Scan all channels and disable them except the current one. * A FORCE can remain from a last transfer having cs_change enabled + * + * In multi mode all FORCE bits must be disabled. */ list_for_each_entry(cs, &ctx->cs, node) { - if (msg->spi->controller_state == cs) + if (msg->spi->controller_state == cs && !mcspi->use_multi_mode) { continue; + } if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE)) { cs->chconf0 &= ~OMAP2_MCSPI_CHCONF_FORCE; From e64d3b6fc9a388d7dc516668651cf4404bffec9b Mon Sep 17 00:00:00 2001 From: Louis Chauvet Date: Wed, 27 Mar 2024 09:43:38 +0100 Subject: [PATCH 3/3] spi: omap2-mcpsi: Enable MULTI-mode in more situations Enable multimode when a transfer of multiple small words can be transformed in a transfer with a single bigger word. This is allowed as long as the result on the cable is the same, so word_delay must be zero. Signed-off-by: Louis Chauvet Link: https://msgid.link/r/20240327-spi-omap2-mcspi-multi-mode-v3-3-c4ac329dd5a2@bootlin.com Signed-off-by: Mark Brown --- drivers/spi/spi-omap2-mcspi.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c index 002f29dbcea6..7e3083b83534 100644 --- a/drivers/spi/spi-omap2-mcspi.c +++ b/drivers/spi/spi-omap2-mcspi.c @@ -1277,11 +1277,24 @@ static int omap2_mcspi_prepare_message(struct spi_controller *ctlr, /* * Check if this transfer contains only one word; + * OR contains 1 to 4 words, with bits_per_word == 8 and no delay between each word + * OR contains 1 to 2 words, with bits_per_word == 16 and no delay between each word + * + * If one of the two last case is true, this also change the bits_per_word of this + * transfer to make it a bit faster. + * It's not an issue to change the bits_per_word here even if the multi-mode is not + * applicable for this message, the signal on the wire will be the same. */ if (bits_per_word < 8 && tr->len == 1) { /* multi-mode is applicable, only one word (1..7 bits) */ + } else if (tr->word_delay.value == 0 && bits_per_word == 8 && tr->len <= 4) { + /* multi-mode is applicable, only one "bigger" word (8,16,24,32 bits) */ + tr->bits_per_word = tr->len * bits_per_word; + } else if (tr->word_delay.value == 0 && bits_per_word == 16 && tr->len <= 2) { + /* multi-mode is applicable, only one "bigger" word (16,32 bits) */ + tr->bits_per_word = tr->len * bits_per_word / 2; } else if (bits_per_word >= 8 && tr->len == bits_per_word / 8) { - /* multi-mode is applicable, only one word (8..32 bits) */ + /* multi-mode is applicable, only one word (9..15,17..32 bits) */ } else { /* multi-mode is not applicable: more than one word in the transfer */ mcspi->use_multi_mode = false;