From d1a7718ee8dbcc488d3243d52e19c755123e0024 Mon Sep 17 00:00:00 2001 From: Jaewon Kim Date: Tue, 2 May 2023 15:28:11 +0900 Subject: [PATCH 1/3] spi: s3c64xx: change polling mode to optional Previously, Polling mode was supported as quirk for SOC without DMA. To provide more flexible support for polling mode, it changed to polling mode when the 'dmas' property is not present in the devicetree, rather than using a quirk. Signed-off-by: Jaewon Kim #define MAX_SPI_PORTS 12 -#define S3C64XX_SPI_QUIRK_POLL (1 << 0) #define S3C64XX_SPI_QUIRK_CS_AUTO (1 << 1) #define AUTOSUSPEND_TIMEOUT 2000 @@ -116,7 +115,7 @@ #define S3C64XX_SPI_TRAILCNT S3C64XX_SPI_MAX_TRAILCNT #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) -#define is_polling(x) (x->port_conf->quirks & S3C64XX_SPI_QUIRK_POLL) +#define is_polling(x) (x->cntrlr_info->polling) #define RXBUSY (1<<2) #define TXBUSY (1<<3) @@ -1068,6 +1067,7 @@ static struct s3c64xx_spi_info *s3c64xx_spi_parse_dt(struct device *dev) } sci->no_cs = of_property_read_bool(dev->of_node, "no-cs-readback"); + sci->polling = !of_property_present(dev->of_node, "dmas"); return sci; } diff --git a/include/linux/platform_data/spi-s3c64xx.h b/include/linux/platform_data/spi-s3c64xx.h index 3101152ce449..1d6e6c424fc6 100644 --- a/include/linux/platform_data/spi-s3c64xx.h +++ b/include/linux/platform_data/spi-s3c64xx.h @@ -36,6 +36,7 @@ struct s3c64xx_spi_info { int src_clk_nr; int num_cs; bool no_cs; + bool polling; int (*cfg_gpio)(void); }; From 3456674f54d3cfdedb28ce8a3db2b6f975392ac8 Mon Sep 17 00:00:00 2001 From: Jaewon Kim Date: Tue, 2 May 2023 15:28:12 +0900 Subject: [PATCH 2/3] spi: s3c64xx: add sleep during transfer In polling mode, the status register is continuously read to check data transfer completion. It can cause excessive CPU usage. To reduce this, we can calculate the transfer time and put the sleep during transfer. When test on ExynosAuto9 SADK board, throughput remained the same, but 100% CPU utilization decreased to 40%. Signed-off-by: Jaewon Kim len * 8 * 1000 / sdd->cur_speed; + /* microsecs to xfer 'len' bytes @ 'cur_speed' */ + time_us = (xfer->len * 8 * 1000 * 1000) / sdd->cur_speed; + ms = (time_us / 1000); ms += 10; /* some tolerance */ + /* sleep during signal transfer time */ + status = readl(regs + S3C64XX_SPI_STATUS); + if (RX_FIFO_LVL(status, sdd) < xfer->len) + usleep_range(time_us / 2, time_us); + val = msecs_to_loops(ms); do { status = readl(regs + S3C64XX_SPI_STATUS); From 1ee806718d5ef7de31c6063c4493f3d6527c9427 Mon Sep 17 00:00:00 2001 From: Jaewon Kim Date: Tue, 2 May 2023 15:28:13 +0900 Subject: [PATCH 3/3] spi: s3c64xx: support interrupt based pio mode Support interrupt based pio mode to optimize cpu usage. When transmitting data size is larget than 32 bytes, operates with interrupt based pio mode. By using the FIFORDY INT, an interrupt can be triggered when the desired size of data has been received. Using this, we can support interrupt based pio mode. Signed-off-by: Jaewon Kim cntrlr_info->polling) @@ -552,7 +556,7 @@ static int s3c64xx_wait_for_dma(struct s3c64xx_spi_driver_data *sdd, } static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd, - struct spi_transfer *xfer) + struct spi_transfer *xfer, bool use_irq) { void __iomem *regs = sdd->regs; unsigned long val; @@ -573,6 +577,12 @@ static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd, if (RX_FIFO_LVL(status, sdd) < xfer->len) usleep_range(time_us / 2, time_us); + if (use_irq) { + val = msecs_to_jiffies(ms); + if (!wait_for_completion_timeout(&sdd->xfer_completion, val)) + return -EIO; + } + val = msecs_to_loops(ms); do { status = readl(regs + S3C64XX_SPI_STATUS); @@ -735,10 +745,13 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master, void *rx_buf = NULL; int target_len = 0, origin_len = 0; int use_dma = 0; + bool use_irq = false; int status; u32 speed; u8 bpw; unsigned long flags; + u32 rdy_lv; + u32 val; reinit_completion(&sdd->xfer_completion); @@ -759,17 +772,46 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master, sdd->rx_dma.ch && sdd->tx_dma.ch) { use_dma = 1; - } else if (xfer->len > fifo_len) { + } else if (xfer->len >= fifo_len) { tx_buf = xfer->tx_buf; rx_buf = xfer->rx_buf; origin_len = xfer->len; - target_len = xfer->len; - if (xfer->len > fifo_len) - xfer->len = fifo_len; + xfer->len = fifo_len - 1; } do { + /* transfer size is greater than 32, change to IRQ mode */ + if (xfer->len > S3C64XX_SPI_POLLING_SIZE) + use_irq = true; + + if (use_irq) { + reinit_completion(&sdd->xfer_completion); + + rdy_lv = xfer->len; + /* Setup RDY_FIFO trigger Level + * RDY_LVL = + * fifo_lvl up to 64 byte -> N bytes + * 128 byte -> RDY_LVL * 2 bytes + * 256 byte -> RDY_LVL * 4 bytes + */ + if (fifo_len == 128) + rdy_lv /= 2; + else if (fifo_len == 256) + rdy_lv /= 4; + + val = readl(sdd->regs + S3C64XX_SPI_MODE_CFG); + val &= ~S3C64XX_SPI_MODE_RX_RDY_LVL; + val |= (rdy_lv << S3C64XX_SPI_MODE_RX_RDY_LVL_SHIFT); + writel(val, sdd->regs + S3C64XX_SPI_MODE_CFG); + + /* Enable FIFO_RDY_EN IRQ */ + val = readl(sdd->regs + S3C64XX_SPI_INT_EN); + writel((val | S3C64XX_SPI_INT_RX_FIFORDY_EN), + sdd->regs + S3C64XX_SPI_INT_EN); + + } + spin_lock_irqsave(&sdd->lock, flags); /* Pending only which is to be done */ @@ -791,7 +833,7 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master, if (use_dma) status = s3c64xx_wait_for_dma(sdd, xfer); else - status = s3c64xx_wait_for_pio(sdd, xfer); + status = s3c64xx_wait_for_pio(sdd, xfer, use_irq); if (status) { dev_err(&spi->dev, @@ -830,8 +872,8 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master, if (xfer->rx_buf) xfer->rx_buf += xfer->len; - if (target_len > fifo_len) - xfer->len = fifo_len; + if (target_len >= fifo_len) + xfer->len = fifo_len - 1; else xfer->len = target_len; } @@ -1001,6 +1043,14 @@ static irqreturn_t s3c64xx_spi_irq(int irq, void *data) dev_err(&spi->dev, "TX underrun\n"); } + if (val & S3C64XX_SPI_ST_RX_FIFORDY) { + complete(&sdd->xfer_completion); + /* No pending clear irq, turn-off INT_EN_RX_FIFO_RDY */ + val = readl(sdd->regs + S3C64XX_SPI_INT_EN); + writel((val & ~S3C64XX_SPI_INT_RX_FIFORDY_EN), + sdd->regs + S3C64XX_SPI_INT_EN); + } + /* Clear the pending irq by setting and then clearing it */ writel(clr, sdd->regs + S3C64XX_SPI_PENDING_CLR); writel(0, sdd->regs + S3C64XX_SPI_PENDING_CLR);