diff options
| -rw-r--r-- | drivers/i2c/busses/i2c-imx-lpi2c.c | 107 |
1 files changed, 83 insertions, 24 deletions
diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c index be7134eefc2f..f97f73faec82 100644 --- a/drivers/i2c/busses/i2c-imx-lpi2c.c +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c @@ -5,6 +5,7 @@ * Copyright 2016 Freescale Semiconductor, Inc. */ +#include <linux/bitfield.h> #include <linux/clk.h> #include <linux/completion.h> #include <linux/delay.h> @@ -90,6 +91,7 @@ #define MRDR_RXEMPTY BIT(14) #define MDER_TDDE BIT(0) #define MDER_RDDE BIT(1) +#define MSR_RDF_ASSERTED(x) FIELD_GET(MSR_RDF, (x)) #define SCR_SEN BIT(0) #define SCR_RST BIT(1) @@ -482,7 +484,7 @@ static bool lpi2c_imx_write_txfifo(struct lpi2c_imx_struct *lpi2c_imx, bool atom static bool lpi2c_imx_read_rxfifo(struct lpi2c_imx_struct *lpi2c_imx, bool atomic) { - unsigned int blocklen, remaining; + unsigned int remaining; unsigned int temp, data; do { @@ -493,15 +495,6 @@ static bool lpi2c_imx_read_rxfifo(struct lpi2c_imx_struct *lpi2c_imx, bool atomi lpi2c_imx->rx_buf[lpi2c_imx->delivered++] = data & 0xff; } while (1); - /* - * First byte is the length of remaining packet in the SMBus block - * data read. Add it to msgs->len. - */ - if (lpi2c_imx->block_data) { - blocklen = lpi2c_imx->rx_buf[0]; - lpi2c_imx->msglen += blocklen; - } - remaining = lpi2c_imx->msglen - lpi2c_imx->delivered; if (!remaining) { @@ -514,12 +507,7 @@ static bool lpi2c_imx_read_rxfifo(struct lpi2c_imx_struct *lpi2c_imx, bool atomi lpi2c_imx_set_rx_watermark(lpi2c_imx); /* multiple receive commands */ - if (lpi2c_imx->block_data) { - lpi2c_imx->block_data = 0; - temp = remaining; - temp |= (RECV_DATA << 8); - writel(temp, lpi2c_imx->base + LPI2C_MTDR); - } else if (!(lpi2c_imx->delivered & 0xff)) { + if (!(lpi2c_imx->delivered & 0xff)) { temp = (remaining > CHUNK_DATA ? CHUNK_DATA : remaining) - 1; temp |= (RECV_DATA << 8); writel(temp, lpi2c_imx->base + LPI2C_MTDR); @@ -557,18 +545,77 @@ static int lpi2c_imx_write_atomic(struct lpi2c_imx_struct *lpi2c_imx, return err; } -static void lpi2c_imx_read_init(struct lpi2c_imx_struct *lpi2c_imx, - struct i2c_msg *msgs) +static unsigned int lpi2c_SMBus_block_read_length_byte(struct lpi2c_imx_struct *lpi2c_imx) { - unsigned int temp; + unsigned int data; + + data = readl(lpi2c_imx->base + LPI2C_MRDR); + lpi2c_imx->rx_buf[lpi2c_imx->delivered++] = data & 0xff; + + return data; +} + +static int lpi2c_imx_read_init(struct lpi2c_imx_struct *lpi2c_imx, + struct i2c_msg *msgs) +{ + unsigned int temp, val, block_len; + int ret; lpi2c_imx->rx_buf = msgs->buf; lpi2c_imx->block_data = msgs->flags & I2C_M_RECV_LEN; lpi2c_imx_set_rx_watermark(lpi2c_imx); - temp = msgs->len > CHUNK_DATA ? CHUNK_DATA - 1 : msgs->len - 1; - temp |= (RECV_DATA << 8); - writel(temp, lpi2c_imx->base + LPI2C_MTDR); + + if (!lpi2c_imx->block_data) { + temp = msgs->len > CHUNK_DATA ? CHUNK_DATA - 1 : msgs->len - 1; + temp |= (RECV_DATA << 8); + writel(temp, lpi2c_imx->base + LPI2C_MTDR); + } else { + /* + * The LPI2C controller automatically sends a NACK after the last byte of a + * receive command, unless the next command in MTDR is also a receive command. + * If MTDR is empty when a receive completes, a NACK is sent by default. + * + * To comply with the SMBus block read spec, we start with a 2-byte read: + * The first byte in RXFIFO is the block length. Once this byte arrives, the + * controller immediately updates MTDR with the next read command, ensuring + * continuous ACK instead of NACK. + * + * The second byte is the first block data byte. Therefore, the subsequent + * read command should request (block_len - 1) bytes, since one data byte + * has already been read. + */ + + writel((RECV_DATA << 8) | 0x01, lpi2c_imx->base + LPI2C_MTDR); + + ret = readl_poll_timeout(lpi2c_imx->base + LPI2C_MSR, val, + MSR_RDF_ASSERTED(val), 1, 1000); + if (ret) { + dev_err(&lpi2c_imx->adapter.dev, "SMBus read count failed %d\n", ret); + return ret; + } + + /* Read block length byte and confirm this SMBus transfer meets protocol */ + block_len = lpi2c_SMBus_block_read_length_byte(lpi2c_imx); + if (block_len == 0 || block_len > I2C_SMBUS_BLOCK_MAX) { + dev_err(&lpi2c_imx->adapter.dev, "Invalid SMBus block read length\n"); + return -EPROTO; + } + + /* + * When block_len shows more bytes need to be read, update second read command to + * keep MTDR non-empty and ensuring continuous ACKs. Only update command register + * here. All block bytes will be read out at IRQ handler or lpi2c_imx_read_atomic() + * function. + */ + if (block_len > 1) + writel((RECV_DATA << 8) | (block_len - 2), lpi2c_imx->base + LPI2C_MTDR); + + lpi2c_imx->msglen += block_len; + msgs->len += block_len; + } + + return 0; } static bool lpi2c_imx_read_chunk_atomic(struct lpi2c_imx_struct *lpi2c_imx) @@ -613,6 +660,10 @@ static bool is_use_dma(struct lpi2c_imx_struct *lpi2c_imx, struct i2c_msg *msg) if (!lpi2c_imx->can_use_dma) return false; + /* DMA is not suitable for SMBus block read */ + if (msg->flags & I2C_M_RECV_LEN) + return false; + /* * When the length of data is less than I2C_DMA_THRESHOLD, * cpu mode is used directly to avoid low performance. @@ -623,10 +674,14 @@ static bool is_use_dma(struct lpi2c_imx_struct *lpi2c_imx, struct i2c_msg *msg) static int lpi2c_imx_pio_xfer(struct lpi2c_imx_struct *lpi2c_imx, struct i2c_msg *msg) { + int ret; + reinit_completion(&lpi2c_imx->complete); if (msg->flags & I2C_M_RD) { - lpi2c_imx_read_init(lpi2c_imx, msg); + ret = lpi2c_imx_read_init(lpi2c_imx, msg); + if (ret) + return ret; lpi2c_imx_intctrl(lpi2c_imx, MIER_RDIE | MIER_NDIE); } else { lpi2c_imx_write(lpi2c_imx, msg); @@ -638,8 +693,12 @@ static int lpi2c_imx_pio_xfer(struct lpi2c_imx_struct *lpi2c_imx, static int lpi2c_imx_pio_xfer_atomic(struct lpi2c_imx_struct *lpi2c_imx, struct i2c_msg *msg) { + int ret; + if (msg->flags & I2C_M_RD) { - lpi2c_imx_read_init(lpi2c_imx, msg); + ret = lpi2c_imx_read_init(lpi2c_imx, msg); + if (ret) + return ret; return lpi2c_imx_read_atomic(lpi2c_imx, msg); } |