From ec679bda639fe84b78d473526ae27c74dea383fb Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Thu, 27 May 2021 23:32:00 +0200 Subject: [PATCH] spi: bcm2835: Allow arbitrary number of slaves Since commit 571e31fa60b3 ("spi: bcm2835: Cache CS register value for ->prepare_message()"), the number of slaves has been limited by a compile-time constant. This was necessitated by statically-sized arrays in the driver private data which contain per-slave register values. As suggested by Mark, move those register values to a per-slave controller_state which is allocated on ->setup and freed on ->cleanup. The limitation on the number of slaves is thus lifted. Signed-off-by: Lukas Wunner Cc: Joe Burmeister Cc: Phil Elwell Link: https://lore.kernel.org/r/a847c01f09400801e74e0630bf5a0197591554da.1622150204.git.lukas@wunner.de Signed-off-by: Mark Brown --- drivers/spi/spi-bcm2835.c | 204 +++++++++++++++++++++++++++------------------- 1 file changed, 119 insertions(+), 85 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index fe40626e45aa..5f8771fe1a31 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -68,7 +68,6 @@ #define BCM2835_SPI_FIFO_SIZE 64 #define BCM2835_SPI_FIFO_SIZE_3_4 48 #define BCM2835_SPI_DMA_MIN_LENGTH 96 -#define BCM2835_SPI_NUM_CS 24 /* raise as necessary */ #define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \ | SPI_NO_CS | SPI_3WIRE) @@ -96,8 +95,6 @@ MODULE_PARM_DESC(polling_limit_us, * @rx_prologue: bytes received without DMA if first RX sglist entry's * length is not a multiple of 4 (to overcome hardware limitation) * @tx_spillover: whether @tx_prologue spills over to second TX sglist entry - * @prepare_cs: precalculated CS register value for ->prepare_message() - * (uses slave-specific clock polarity and phase settings) * @debugfs_dir: the debugfs directory - neede to remove debugfs when * unloading the module * @count_transfer_polling: count of how often polling mode is used @@ -107,7 +104,7 @@ MODULE_PARM_DESC(polling_limit_us, * These are counted as well in @count_transfer_polling and * @count_transfer_irq * @count_transfer_dma: count how often dma mode is used - * @chip_select: SPI slave currently selected + * @slv: SPI slave currently selected * (used by bcm2835_spi_dma_tx_done() to write @clear_rx_cs) * @tx_dma_active: whether a TX DMA descriptor is in progress * @rx_dma_active: whether a RX DMA descriptor is in progress @@ -115,11 +112,6 @@ MODULE_PARM_DESC(polling_limit_us, * @fill_tx_desc: preallocated TX DMA descriptor used for RX-only transfers * (cyclically copies from zero page to TX FIFO) * @fill_tx_addr: bus address of zero page - * @clear_rx_desc: preallocated RX DMA descriptor used for TX-only transfers - * (cyclically clears RX FIFO by writing @clear_rx_cs to CS register) - * @clear_rx_addr: bus address of @clear_rx_cs - * @clear_rx_cs: precalculated CS register value to clear RX FIFO - * (uses slave-specific clock polarity and phase settings) */ struct bcm2835_spi { void __iomem *regs; @@ -134,7 +126,6 @@ struct bcm2835_spi { int tx_prologue; int rx_prologue; unsigned int tx_spillover; - u32 prepare_cs[BCM2835_SPI_NUM_CS]; struct dentry *debugfs_dir; u64 count_transfer_polling; @@ -142,14 +133,28 @@ struct bcm2835_spi { u64 count_transfer_irq_after_polling; u64 count_transfer_dma; - u8 chip_select; + struct bcm2835_spidev *slv; unsigned int tx_dma_active; unsigned int rx_dma_active; struct dma_async_tx_descriptor *fill_tx_desc; dma_addr_t fill_tx_addr; - struct dma_async_tx_descriptor *clear_rx_desc[BCM2835_SPI_NUM_CS]; +}; + +/** + * struct bcm2835_spidev - BCM2835 SPI slave + * @prepare_cs: precalculated CS register value for ->prepare_message() + * (uses slave-specific clock polarity and phase settings) + * @clear_rx_desc: preallocated RX DMA descriptor used for TX-only transfers + * (cyclically clears RX FIFO by writing @clear_rx_cs to CS register) + * @clear_rx_addr: bus address of @clear_rx_cs + * @clear_rx_cs: precalculated CS register value to clear RX FIFO + * (uses slave-specific clock polarity and phase settings) + */ +struct bcm2835_spidev { + u32 prepare_cs; + struct dma_async_tx_descriptor *clear_rx_desc; dma_addr_t clear_rx_addr; - u32 clear_rx_cs[BCM2835_SPI_NUM_CS] ____cacheline_aligned; + u32 clear_rx_cs ____cacheline_aligned; }; #if defined(CONFIG_DEBUG_FS) @@ -624,8 +629,7 @@ static void bcm2835_spi_dma_tx_done(void *data) /* busy-wait for TX FIFO to empty */ while (!(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_DONE)) - bcm2835_wr(bs, BCM2835_SPI_CS, - bs->clear_rx_cs[bs->chip_select]); + bcm2835_wr(bs, BCM2835_SPI_CS, bs->slv->clear_rx_cs); bs->tx_dma_active = false; smp_wmb(); @@ -646,18 +650,18 @@ static void bcm2835_spi_dma_tx_done(void *data) /** * bcm2835_spi_prepare_sg() - prepare and submit DMA descriptor for sglist * @ctlr: SPI master controller - * @spi: SPI slave * @tfr: SPI transfer * @bs: BCM2835 SPI controller + * @slv: BCM2835 SPI slave * @is_tx: whether to submit DMA descriptor for TX or RX sglist * * Prepare and submit a DMA descriptor for the TX or RX sglist of @tfr. * Return 0 on success or a negative error number. */ static int bcm2835_spi_prepare_sg(struct spi_controller *ctlr, - struct spi_device *spi, struct spi_transfer *tfr, struct bcm2835_spi *bs, + struct bcm2835_spidev *slv, bool is_tx) { struct dma_chan *chan; @@ -697,7 +701,7 @@ static int bcm2835_spi_prepare_sg(struct spi_controller *ctlr, } else if (!tfr->rx_buf) { desc->callback = bcm2835_spi_dma_tx_done; desc->callback_param = ctlr; - bs->chip_select = spi->chip_select; + bs->slv = slv; } /* submit it to DMA-engine */ @@ -709,8 +713,8 @@ static int bcm2835_spi_prepare_sg(struct spi_controller *ctlr, /** * bcm2835_spi_transfer_one_dma() - perform SPI transfer using DMA engine * @ctlr: SPI master controller - * @spi: SPI slave * @tfr: SPI transfer + * @slv: BCM2835 SPI slave * @cs: CS register * * For *bidirectional* transfers (both tx_buf and rx_buf are non-%NULL), set up @@ -754,8 +758,8 @@ static int bcm2835_spi_prepare_sg(struct spi_controller *ctlr, * performed at the end of an RX-only transfer. */ static int bcm2835_spi_transfer_one_dma(struct spi_controller *ctlr, - struct spi_device *spi, struct spi_transfer *tfr, + struct bcm2835_spidev *slv, u32 cs) { struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr); @@ -773,7 +777,7 @@ static int bcm2835_spi_transfer_one_dma(struct spi_controller *ctlr, /* setup tx-DMA */ if (bs->tx_buf) { - ret = bcm2835_spi_prepare_sg(ctlr, spi, tfr, bs, true); + ret = bcm2835_spi_prepare_sg(ctlr, tfr, bs, slv, true); } else { cookie = dmaengine_submit(bs->fill_tx_desc); ret = dma_submit_error(cookie); @@ -799,9 +803,9 @@ static int bcm2835_spi_transfer_one_dma(struct spi_controller *ctlr, * this saves 10us or more. */ if (bs->rx_buf) { - ret = bcm2835_spi_prepare_sg(ctlr, spi, tfr, bs, false); + ret = bcm2835_spi_prepare_sg(ctlr, tfr, bs, slv, false); } else { - cookie = dmaengine_submit(bs->clear_rx_desc[spi->chip_select]); + cookie = dmaengine_submit(slv->clear_rx_desc); ret = dma_submit_error(cookie); } if (ret) { @@ -850,8 +854,6 @@ static bool bcm2835_spi_can_dma(struct spi_controller *ctlr, static void bcm2835_dma_release(struct spi_controller *ctlr, struct bcm2835_spi *bs) { - int i; - if (ctlr->dma_tx) { dmaengine_terminate_sync(ctlr->dma_tx); @@ -870,17 +872,6 @@ static void bcm2835_dma_release(struct spi_controller *ctlr, if (ctlr->dma_rx) { dmaengine_terminate_sync(ctlr->dma_rx); - - for (i = 0; i < BCM2835_SPI_NUM_CS; i++) - if (bs->clear_rx_desc[i]) - dmaengine_desc_free(bs->clear_rx_desc[i]); - - if (bs->clear_rx_addr) - dma_unmap_single(ctlr->dma_rx->device->dev, - bs->clear_rx_addr, - sizeof(bs->clear_rx_cs), - DMA_TO_DEVICE); - dma_release_channel(ctlr->dma_rx); ctlr->dma_rx = NULL; } @@ -892,7 +883,7 @@ static int bcm2835_dma_init(struct spi_controller *ctlr, struct device *dev, struct dma_slave_config slave_config; const __be32 *addr; dma_addr_t dma_reg_base; - int ret, i; + int ret; /* base address in dma-space */ addr = of_get_address(ctlr->dev.of_node, 0, NULL, NULL); @@ -972,35 +963,6 @@ static int bcm2835_dma_init(struct spi_controller *ctlr, struct device *dev, if (ret) goto err_config; - bs->clear_rx_addr = dma_map_single(ctlr->dma_rx->device->dev, - bs->clear_rx_cs, - sizeof(bs->clear_rx_cs), - DMA_TO_DEVICE); - if (dma_mapping_error(ctlr->dma_rx->device->dev, bs->clear_rx_addr)) { - dev_err(dev, "cannot map clear_rx_cs - not using DMA mode\n"); - bs->clear_rx_addr = 0; - ret = -ENOMEM; - goto err_release; - } - - for (i = 0; i < BCM2835_SPI_NUM_CS; i++) { - bs->clear_rx_desc[i] = dmaengine_prep_dma_cyclic(ctlr->dma_rx, - bs->clear_rx_addr + i * sizeof(u32), - sizeof(u32), 0, - DMA_MEM_TO_DEV, 0); - if (!bs->clear_rx_desc[i]) { - dev_err(dev, "cannot prepare clear_rx_desc - not using DMA mode\n"); - ret = -ENOMEM; - goto err_release; - } - - ret = dmaengine_desc_set_reuse(bs->clear_rx_desc[i]); - if (ret) { - dev_err(dev, "cannot reuse clear_rx_desc - not using DMA mode\n"); - goto err_release; - } - } - /* all went well, so set can_dma */ ctlr->can_dma = bcm2835_spi_can_dma; @@ -1082,9 +1044,10 @@ static int bcm2835_spi_transfer_one(struct spi_controller *ctlr, struct spi_transfer *tfr) { struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr); + struct bcm2835_spidev *slv = spi_get_ctldata(spi); unsigned long spi_hz, clk_hz, cdiv; unsigned long hz_per_byte, byte_limit; - u32 cs = bs->prepare_cs[spi->chip_select]; + u32 cs = slv->prepare_cs; /* set clock */ spi_hz = tfr->speed_hz; @@ -1133,7 +1096,7 @@ static int bcm2835_spi_transfer_one(struct spi_controller *ctlr, * this 1 idle clock cycle pattern but runs the spi clock without gaps */ if (ctlr->can_dma && bcm2835_spi_can_dma(ctlr, spi, tfr)) - return bcm2835_spi_transfer_one_dma(ctlr, spi, tfr, cs); + return bcm2835_spi_transfer_one_dma(ctlr, tfr, slv, cs); /* run in interrupt-mode */ return bcm2835_spi_transfer_one_irq(ctlr, spi, tfr, cs, true); @@ -1144,6 +1107,7 @@ static int bcm2835_spi_prepare_message(struct spi_controller *ctlr, { struct spi_device *spi = msg->spi; struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr); + struct bcm2835_spidev *slv = spi_get_ctldata(spi); int ret; if (ctlr->can_dma) { @@ -1162,7 +1126,7 @@ static int bcm2835_spi_prepare_message(struct spi_controller *ctlr, * Set up clock polarity before spi_transfer_one_message() asserts * chip select to avoid a gratuitous clock signal edge. */ - bcm2835_wr(bs, BCM2835_SPI_CS, bs->prepare_cs[spi->chip_select]); + bcm2835_wr(bs, BCM2835_SPI_CS, slv->prepare_cs); return 0; } @@ -1188,17 +1152,81 @@ static int chip_match_name(struct gpio_chip *chip, void *data) return !strcmp(chip->label, data); } +static void bcm2835_spi_cleanup(struct spi_device *spi) +{ + struct bcm2835_spidev *slv = spi_get_ctldata(spi); + struct spi_controller *ctlr = spi->controller; + + if (slv->clear_rx_desc) + dmaengine_desc_free(slv->clear_rx_desc); + + if (slv->clear_rx_addr) + dma_unmap_single(ctlr->dma_rx->device->dev, + slv->clear_rx_addr, + sizeof(u32), + DMA_TO_DEVICE); + + kfree(slv); +} + +static int bcm2835_spi_setup_dma(struct spi_controller *ctlr, + struct spi_device *spi, + struct bcm2835_spi *bs, + struct bcm2835_spidev *slv) +{ + int ret; + + if (!ctlr->dma_rx) + return 0; + + slv->clear_rx_addr = dma_map_single(ctlr->dma_rx->device->dev, + &slv->clear_rx_cs, + sizeof(u32), + DMA_TO_DEVICE); + if (dma_mapping_error(ctlr->dma_rx->device->dev, slv->clear_rx_addr)) { + dev_err(&spi->dev, "cannot map clear_rx_cs\n"); + slv->clear_rx_addr = 0; + return -ENOMEM; + } + + slv->clear_rx_desc = dmaengine_prep_dma_cyclic(ctlr->dma_rx, + slv->clear_rx_addr, + sizeof(u32), 0, + DMA_MEM_TO_DEV, 0); + if (!slv->clear_rx_desc) { + dev_err(&spi->dev, "cannot prepare clear_rx_desc\n"); + return -ENOMEM; + } + + ret = dmaengine_desc_set_reuse(slv->clear_rx_desc); + if (ret) { + dev_err(&spi->dev, "cannot reuse clear_rx_desc\n"); + return ret; + } + + return 0; +} + static int bcm2835_spi_setup(struct spi_device *spi) { struct spi_controller *ctlr = spi->controller; struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr); + struct bcm2835_spidev *slv = spi_get_ctldata(spi); struct gpio_chip *chip; + int ret; u32 cs; - if (spi->chip_select >= BCM2835_SPI_NUM_CS) { - dev_err(&spi->dev, "only %d chip-selects supported\n", - BCM2835_SPI_NUM_CS - 1); - return -EINVAL; + if (!slv) { + slv = kzalloc(ALIGN(sizeof(*slv), dma_get_cache_alignment()), + GFP_KERNEL); + if (!slv) + return -ENOMEM; + + spi_set_ctldata(spi, slv); + + ret = bcm2835_spi_setup_dma(ctlr, spi, bs, slv); + if (ret) + goto err_cleanup; } /* @@ -1212,20 +1240,19 @@ static int bcm2835_spi_setup(struct spi_device *spi) cs |= BCM2835_SPI_CS_CPOL; if (spi->mode & SPI_CPHA) cs |= BCM2835_SPI_CS_CPHA; - bs->prepare_cs[spi->chip_select] = cs; + slv->prepare_cs = cs; /* * Precalculate SPI slave's CS register value to clear RX FIFO * in case of a TX-only DMA transfer. */ if (ctlr->dma_rx) { - bs->clear_rx_cs[spi->chip_select] = cs | - BCM2835_SPI_CS_TA | - BCM2835_SPI_CS_DMAEN | - BCM2835_SPI_CS_CLEAR_RX; + slv->clear_rx_cs = cs | BCM2835_SPI_CS_TA | + BCM2835_SPI_CS_DMAEN | + BCM2835_SPI_CS_CLEAR_RX; dma_sync_single_for_device(ctlr->dma_rx->device->dev, - bs->clear_rx_addr, - sizeof(bs->clear_rx_cs), + slv->clear_rx_addr, + sizeof(u32), DMA_TO_DEVICE); } @@ -1247,7 +1274,8 @@ static int bcm2835_spi_setup(struct spi_device *spi) */ dev_err(&spi->dev, "setup: only two native chip-selects are supported\n"); - return -EINVAL; + ret = -EINVAL; + goto err_cleanup; } /* @@ -1268,14 +1296,20 @@ static int bcm2835_spi_setup(struct spi_device *spi) DRV_NAME, GPIO_LOOKUP_FLAGS_DEFAULT, GPIOD_OUT_LOW); - if (IS_ERR(spi->cs_gpiod)) - return PTR_ERR(spi->cs_gpiod); + if (IS_ERR(spi->cs_gpiod)) { + ret = PTR_ERR(spi->cs_gpiod); + goto err_cleanup; + } /* and set up the "mode" and level */ dev_info(&spi->dev, "setting up native-CS%i to use GPIO\n", spi->chip_select); return 0; + +err_cleanup: + bcm2835_spi_cleanup(spi); + return ret; } static int bcm2835_spi_probe(struct platform_device *pdev) @@ -1284,8 +1318,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) struct bcm2835_spi *bs; int err; - ctlr = devm_spi_alloc_master(&pdev->dev, ALIGN(sizeof(*bs), - dma_get_cache_alignment())); + ctlr = devm_spi_alloc_master(&pdev->dev, sizeof(*bs)); if (!ctlr) return -ENOMEM; @@ -1296,6 +1329,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) ctlr->bits_per_word_mask = SPI_BPW_MASK(8); ctlr->num_chipselect = 3; ctlr->setup = bcm2835_spi_setup; + ctlr->cleanup = bcm2835_spi_cleanup; ctlr->transfer_one = bcm2835_spi_transfer_one; ctlr->handle_err = bcm2835_spi_handle_err; ctlr->prepare_message = bcm2835_spi_prepare_message; -- 2.11.0