From 6ac25538d870685707e7cdebba771c79ada77e80 Mon Sep 17 00:00:00 2001 From: Eddie James Date: Wed, 11 May 2022 15:52:03 -0500 Subject: [PATCH 1/3] i2c: ast_i2c: Remove SCL direct drive mode SCL direct drive mode prevents communication with devices that do clock stretching, so disable. The Linux driver doesn't use this mode, and the engine can handle clock stretching. Signed-off-by: Eddie James Reviewed-by: Heiko Schocher Reviewed-by: Joel Stanley Reviewed-by: ryan_chen --- drivers/i2c/ast_i2c.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/i2c/ast_i2c.c b/drivers/i2c/ast_i2c.c index c9ffe2d6282..1c1d5566dad 100644 --- a/drivers/i2c/ast_i2c.c +++ b/drivers/i2c/ast_i2c.c @@ -77,7 +77,7 @@ static void ast_i2c_init_bus(struct udevice *dev) /* Enable Master Mode. Assuming single-master */ writel(I2CD_MASTER_EN | I2CD_M_SDA_LOCK_EN - | I2CD_MULTI_MASTER_DIS | I2CD_M_SCL_DRIVE_EN, + | I2CD_MULTI_MASTER_DIS, &priv->regs->fcr); /* Enable Interrupts */ writel(I2CD_INTR_TX_ACK From 2b77eea7f309d969310f5d4c2d9639ffca2b5abf Mon Sep 17 00:00:00 2001 From: Jim Liu Date: Thu, 23 Jun 2022 13:31:42 +0800 Subject: [PATCH 2/3] i2c: nuvoton: Add NPCM7xx i2c driver Add Nuvoton BMC NPCM750 i2c driver Signed-off-by: Jim Liu Reviewed-by: Heiko Schocher --- drivers/i2c/Kconfig | 5 + drivers/i2c/Makefile | 1 + drivers/i2c/npcm-i2c.c | 630 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 636 insertions(+) create mode 100644 drivers/i2c/npcm-i2c.c diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index 72d06e4972b..be4724bf8ef 100644 --- a/drivers/i2c/Kconfig +++ b/drivers/i2c/Kconfig @@ -447,6 +447,11 @@ config SYS_I2C_NEXELL have several I2C ports and all are provided, controlled by the device tree. +config SYS_I2C_NPCM + bool "Nuvoton NPCM I2C driver" + help + Support for Nuvoton I2C controller driver. + config SYS_I2C_OCORES bool "ocores I2C driver" depends on DM_I2C diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile index 9d41f379bbc..7e046f809a4 100644 --- a/drivers/i2c/Makefile +++ b/drivers/i2c/Makefile @@ -33,6 +33,7 @@ obj-$(CONFIG_SYS_I2C_MV) += mv_i2c.o obj-$(CONFIG_SYS_I2C_MVTWSI) += mvtwsi.o obj-$(CONFIG_SYS_I2C_MXC) += mxc_i2c.o obj-$(CONFIG_SYS_I2C_NEXELL) += nx_i2c.o +obj-$(CONFIG_SYS_I2C_NPCM) += npcm_i2c.o obj-$(CONFIG_SYS_I2C_OCORES) += ocores_i2c.o obj-$(CONFIG_SYS_I2C_OCTEON) += octeon_i2c.o obj-$(CONFIG_SYS_I2C_OMAP24XX) += omap24xx_i2c.o diff --git a/drivers/i2c/npcm-i2c.c b/drivers/i2c/npcm-i2c.c new file mode 100644 index 00000000000..ea4ef532565 --- /dev/null +++ b/drivers/i2c/npcm-i2c.c @@ -0,0 +1,630 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (c) 2021 Nuvoton Technology Corp. + */ + +#include +#include +#include +#include +#include +#include + +#define I2C_FREQ_100K 100000 +#define NPCM_I2C_TIMEOUT_MS 10 +#define NPCM7XX_I2CSEGCTL_INIT_VAL 0x0333F000 +#define NPCM8XX_I2CSEGCTL_INIT_VAL 0x9333F000 + +/* SCLFRQ min/max field values */ +#define SCLFRQ_MIN 10 +#define SCLFRQ_MAX 511 + +/* SMBCTL1 */ +#define SMBCTL1_START BIT(0) +#define SMBCTL1_STOP BIT(1) +#define SMBCTL1_INTEN BIT(2) +#define SMBCTL1_ACK BIT(4) +#define SMBCTL1_STASTRE BIT(7) + +/* SMBCTL2 */ +#define SMBCTL2_ENABLE BIT(0) + +/* SMBCTL3 */ +#define SMBCTL3_SCL_LVL BIT(7) +#define SMBCTL3_SDA_LVL BIT(6) + +/* SMBCST */ +#define SMBCST_BB BIT(1) +#define SMBCST_TGSCL BIT(5) + +/* SMBST */ +#define SMBST_XMIT BIT(0) +#define SMBST_MASTER BIT(1) +#define SMBST_STASTR BIT(3) +#define SMBST_NEGACK BIT(4) +#define SMBST_BER BIT(5) +#define SMBST_SDAST BIT(6) + +/* SMBCST3 in bank0 */ +#define SMBCST3_EO_BUSY BIT(7) + +/* SMBFIF_CTS in bank1 */ +#define SMBFIF_CTS_CLR_FIFO BIT(6) + +#define SMBFIF_CTL_FIFO_EN BIT(4) +#define SMBCTL3_BNK_SEL BIT(5) + +enum { + I2C_ERR_NACK = 1, + I2C_ERR_BER, + I2C_ERR_TIMEOUT, +}; + +struct smb_bank0_regs { + u8 addr3; + u8 addr7; + u8 addr4; + u8 addr8; + u16 addr5; + u16 addr6; + u8 cst2; + u8 cst3; + u8 ctl4; + u8 ctl5; + u8 scllt; + u8 fif_ctl; + u8 sclht; +}; + +struct smb_bank1_regs { + u8 fif_cts; + u8 fair_per; + u16 txf_ctl; + u32 t_out; + u8 cst2; + u8 cst3; + u16 txf_sts; + u16 rxf_sts; + u8 rxf_ctl; +}; + +struct npcm_i2c_regs { + u16 sda; + u16 st; + u16 cst; + u16 ctl1; + u16 addr; + u16 ctl2; + u16 addr2; + u16 ctl3; + union { + struct smb_bank0_regs bank0; + struct smb_bank1_regs bank1; + }; + +}; + +struct npcm_i2c_bus { + struct npcm_i2c_regs *reg; + int num; + u32 apb_clk; + u32 freq; + bool started; +}; + +static void npcm_dump_regs(struct npcm_i2c_bus *bus) +{ + struct npcm_i2c_regs *reg = bus->reg; + + printf("\n"); + printf("SMBST=0x%x\n", readb(®->st)); + printf("SMBCST=0x%x\n", readb(®->cst)); + printf("SMBCTL1=0x%x\n", readb(®->ctl1)); + printf("\n"); +} + +static int npcm_i2c_check_sda(struct npcm_i2c_bus *bus) +{ + struct npcm_i2c_regs *reg = bus->reg; + ulong start_time; + int err = I2C_ERR_TIMEOUT; + u8 val; + + start_time = get_timer(0); + /* wait SDAST to be 1 */ + while (get_timer(start_time) < NPCM_I2C_TIMEOUT_MS) { + val = readb(®->st); + if (val & SMBST_NEGACK) { + err = I2C_ERR_NACK; + break; + } + if (val & SMBST_BER) { + err = I2C_ERR_BER; + break; + } + if (val & SMBST_SDAST) { + err = 0; + break; + } + } + + if (err) + printf("%s: err %d\n", __func__, err); + + return err; +} + +static int npcm_i2c_send_start(struct npcm_i2c_bus *bus) +{ + struct npcm_i2c_regs *reg = bus->reg; + ulong start_time; + int err = I2C_ERR_TIMEOUT; + + /* Generate START condition */ + setbits_8(®->ctl1, SMBCTL1_START); + + start_time = get_timer(0); + while (get_timer(start_time) < NPCM_I2C_TIMEOUT_MS) { + if (readb(®->st) & SMBST_BER) + return I2C_ERR_BER; + if (readb(®->st) & SMBST_MASTER) { + err = 0; + break; + } + } + bus->started = true; + + return err; +} + +static int npcm_i2c_send_stop(struct npcm_i2c_bus *bus, bool wait) +{ + struct npcm_i2c_regs *reg = bus->reg; + ulong start_time; + int err = I2C_ERR_TIMEOUT; + + setbits_8(®->ctl1, SMBCTL1_STOP); + + /* Clear NEGACK, STASTR and BER bits */ + writeb(SMBST_STASTR | SMBST_NEGACK | SMBST_BER, ®->st); + + bus->started = false; + + if (!wait) + return 0; + + start_time = get_timer(0); + while (get_timer(start_time) < NPCM_I2C_TIMEOUT_MS) { + if ((readb(®->ctl1) & SMBCTL1_STOP) == 0) { + err = 0; + break; + } + } + if (err) { + printf("%s: err %d\n", __func__, err); + npcm_dump_regs(bus); + } + + return err; +} + +static void npcm_i2c_reset(struct npcm_i2c_bus *bus) +{ + struct npcm_i2c_regs *reg = bus->reg; + + debug("%s: module %d\n", __func__, bus->num); + /* disable & enable SMB moudle */ + clrbits_8(®->ctl2, SMBCTL2_ENABLE); + setbits_8(®->ctl2, SMBCTL2_ENABLE); + + /* clear BB and status */ + writeb(SMBCST_BB, ®->cst); + writeb(0xff, ®->st); + + /* select bank 1 */ + setbits_8(®->ctl3, SMBCTL3_BNK_SEL); + /* Clear all fifo bits */ + writeb(SMBFIF_CTS_CLR_FIFO, ®->bank1.fif_cts); + + /* select bank 0 */ + clrbits_8(®->ctl3, SMBCTL3_BNK_SEL); + /* clear EOB bit */ + writeb(SMBCST3_EO_BUSY, ®->bank0.cst3); + /* single byte mode */ + clrbits_8(®->bank0.fif_ctl, SMBFIF_CTL_FIFO_EN); + + /* set POLL mode */ + writeb(0, ®->ctl1); +} + +static void npcm_i2c_recovery(struct npcm_i2c_bus *bus, u32 addr) +{ + u8 val; + int iter = 27; + struct npcm_i2c_regs *reg = bus->reg; + int err; + + val = readb(®->ctl3); + /* Skip recovery, bus not stucked */ + if ((val & SMBCTL3_SCL_LVL) && (val & SMBCTL3_SDA_LVL)) + return; + + printf("Performing I2C bus %d recovery...\n", bus->num); + /* SCL/SDA are not releaed, perform recovery */ + while (1) { + /* toggle SCL line */ + writeb(SMBCST_TGSCL, ®->cst); + + udelay(20); + val = readb(®->ctl3); + if (val & SMBCTL3_SDA_LVL) + break; + if (iter-- == 0) + break; + } + + if (val & SMBCTL3_SDA_LVL) { + writeb((u8)((addr << 1) & 0xff), ®->sda); + err = npcm_i2c_send_start(bus); + if (!err) { + udelay(20); + npcm_i2c_send_stop(bus, false); + udelay(200); + printf("I2C bus %d recovery completed\n", + bus->num); + } else { + printf("%s: send START err %d\n", __func__, err); + } + } else { + printf("Fail to recover I2C bus %d\n", bus->num); + } + npcm_i2c_reset(bus); +} + +static int npcm_i2c_send_address(struct npcm_i2c_bus *bus, u8 addr, + bool stall) +{ + struct npcm_i2c_regs *reg = bus->reg; + ulong start_time; + u8 val; + + /* Stall After Start Enable */ + if (stall) + setbits_8(®->ctl1, SMBCTL1_STASTRE); + + writeb(addr, ®->sda); + if (stall) { + start_time = get_timer(0); + while (get_timer(start_time) < NPCM_I2C_TIMEOUT_MS) { + if (readb(®->st) & SMBST_STASTR) + break; + + if (readb(®->st) & SMBST_BER) { + clrbits_8(®->ctl1, SMBCTL1_STASTRE); + return I2C_ERR_BER; + } + } + } + + /* check ACK */ + val = readb(®->st); + if (val & SMBST_NEGACK) { + debug("NACK on addr 0x%x\n", addr >> 1); + /* After a Stop condition, writing 1 to NEGACK clears it */ + return I2C_ERR_NACK; + } + if (val & SMBST_BER) + return I2C_ERR_BER; + + return 0; +} + +static int npcm_i2c_read_bytes(struct npcm_i2c_bus *bus, u8 *data, int len) +{ + struct npcm_i2c_regs *reg = bus->reg; + u8 val; + int i; + int err = 0; + + if (len == 1) { + /* bus should be stalled before receiving last byte */ + setbits_8(®->ctl1, SMBCTL1_ACK); + + /* clear STASTRE if it is set */ + if (readb(®->ctl1) & SMBCTL1_STASTRE) { + writeb(SMBST_STASTR, ®->st); + clrbits_8(®->ctl1, SMBCTL1_STASTRE); + } + npcm_i2c_check_sda(bus); + npcm_i2c_send_stop(bus, false); + *data = readb(®->sda); + /* this must be done to generate STOP condition */ + writeb(SMBST_NEGACK, ®->st); + } else { + for (i = 0; i < len; i++) { + /* + * When NEGACK bit is set to 1 after the transmission of a byte, + * SDAST is not set to 1. + */ + if (i != (len - 1)) { + err = npcm_i2c_check_sda(bus); + } else { + err = readb_poll_timeout(®->ctl1, val, + !(val & SMBCTL1_ACK), 100000); + if (err) { + printf("wait nack timeout\n"); + err = I2C_ERR_TIMEOUT; + npcm_dump_regs(bus); + } + } + if (err && err != I2C_ERR_TIMEOUT) + break; + if (i == (len - 2)) { + /* set NACK before last byte */ + setbits_8(®->ctl1, SMBCTL1_ACK); + } + if (i == (len - 1)) { + /* last byte, send STOP condition */ + npcm_i2c_send_stop(bus, false); + *data = readb(®->sda); + writeb(SMBST_NEGACK, ®->st); + break; + } + *data = readb(®->sda); + data++; + } + } + + return err; +} + +static int npcm_i2c_send_bytes(struct npcm_i2c_bus *bus, u8 *data, int len) +{ + struct npcm_i2c_regs *reg = bus->reg; + u8 val; + int i; + int err = 0; + + val = readb(®->st); + if (val & SMBST_NEGACK) + return I2C_ERR_NACK; + else if (val & SMBST_BER) + return I2C_ERR_BER; + + /* clear STASTRE if it is set */ + if (readb(®->ctl1) & SMBCTL1_STASTRE) + clrbits_8(®->ctl1, SMBCTL1_STASTRE); + + for (i = 0; i < len; i++) { + err = npcm_i2c_check_sda(bus); + if (err) + break; + writeb(*data, ®->sda); + data++; + } + npcm_i2c_check_sda(bus); + + return err; +} + +static int npcm_i2c_read(struct npcm_i2c_bus *bus, u32 addr, u8 *data, + u32 len) +{ + struct npcm_i2c_regs *reg = bus->reg; + int err; + bool stall; + + if (len <= 0) + return -EINVAL; + + /* send START condition */ + err = npcm_i2c_send_start(bus); + if (err) { + debug("%s: send START err %d\n", __func__, err); + return err; + } + + stall = (len == 1) ? true : false; + /* send address byte */ + err = npcm_i2c_send_address(bus, (u8)(addr << 1) | 0x1, stall); + + if (!err && len) + npcm_i2c_read_bytes(bus, data, len); + + if (err == I2C_ERR_NACK) { + /* clear NACK */ + writeb(SMBST_NEGACK, ®->st); + } + + if (err) + debug("%s: err %d\n", __func__, err); + + return err; +} + +static int npcm_i2c_write(struct npcm_i2c_bus *bus, u32 addr, u8 *data, + u32 len) +{ + struct npcm_i2c_regs *reg = bus->reg; + int err; + bool stall; + + /* send START condition */ + err = npcm_i2c_send_start(bus); + if (err) { + debug("%s: send START err %d\n", __func__, err); + return err; + } + + stall = (len == 0) ? true : false; + /* send address byte */ + err = npcm_i2c_send_address(bus, (u8)(addr << 1), stall); + + if (!err && len) + err = npcm_i2c_send_bytes(bus, data, len); + + /* clear STASTRE if it is set */ + if (stall) + clrbits_8(®->ctl1, SMBCTL1_STASTRE); + + if (err) + debug("%s: err %d\n", __func__, err); + + return err; +} + +static int npcm_i2c_xfer(struct udevice *dev, + struct i2c_msg *msg, int nmsgs) +{ + struct npcm_i2c_bus *bus = dev_get_priv(dev); + struct npcm_i2c_regs *reg = bus->reg; + int ret = 0, err = 0; + + if (nmsgs < 1 || nmsgs > 2) { + printf("%s: commands not support\n", __func__); + return -EREMOTEIO; + } + /* clear ST register */ + writeb(0xFF, ®->st); + + for ( ; nmsgs > 0; nmsgs--, msg++) { + if (msg->flags & I2C_M_RD) + err = npcm_i2c_read(bus, msg->addr, msg->buf, + msg->len); + else + err = npcm_i2c_write(bus, msg->addr, msg->buf, + msg->len); + if (err) { + debug("i2c_xfer: error %d\n", err); + ret = -EREMOTEIO; + break; + } + } + + if (bus->started) + npcm_i2c_send_stop(bus, true); + + if (err) + npcm_i2c_recovery(bus, msg->addr); + + return ret; +} + +static int npcm_i2c_init_clk(struct npcm_i2c_bus *bus, u32 bus_freq) +{ + struct npcm_i2c_regs *reg = bus->reg; + u32 freq = bus->apb_clk; + u32 sclfrq; + u8 hldt, val; + + if (bus_freq > I2C_FREQ_100K) { + printf("Support standard mode only\n"); + return -EINVAL; + } + + /* SCLFRQ = T(SCL)/4/T(CLK) = FREQ(CLK)/4/FREQ(SCL) */ + sclfrq = freq / (bus_freq * 4); + if (sclfrq < SCLFRQ_MIN || sclfrq > SCLFRQ_MAX) + return -EINVAL; + + if (freq >= 40000000) + hldt = 17; + else if (freq >= 12500000) + hldt = 15; + else + hldt = 7; + + val = readb(®->ctl2) & 0x1; + val |= (sclfrq & 0x7F) << 1; + writeb(val, ®->ctl2); + + /* clear 400K_MODE bit */ + val = readb(®->ctl3) & 0xc; + val |= (sclfrq >> 7) & 0x3; + writeb(val, ®->ctl3); + + writeb(hldt, ®->bank0.ctl4); + + return 0; +} + +static int npcm_i2c_set_bus_speed(struct udevice *dev, + unsigned int speed) +{ + struct npcm_i2c_bus *bus = dev_get_priv(dev); + + return npcm_i2c_init_clk(bus, speed); +} + +static int npcm_i2c_probe(struct udevice *dev) +{ + struct npcm_i2c_bus *bus = dev_get_priv(dev); + struct npcm_gcr *gcr = (struct npcm_gcr *)NPCM_GCR_BA; + struct npcm_i2c_regs *reg; + u32 i2csegctl_val = dev_get_driver_data(dev); + struct clk clk; + int ret; + + ret = clk_get_by_index(dev, 0, &clk); + if (ret) { + printf("%s: ret %d\n", __func__, ret); + return ret; + } + bus->apb_clk = clk_get_rate(&clk); + if (bus->apb_clk <= 0) { + printf("%s: fail to get rate\n", __func__); + return -EINVAL; + } + clk_free(&clk); + + bus->num = dev->seq_; + bus->reg = dev_read_addr_ptr(dev); + bus->freq = dev_read_u32_default(dev, "clock-frequency", 100000); + bus->started = false; + reg = bus->reg; + + if (npcm_i2c_init_clk(bus, bus->freq)) { + printf("%s: init_clk failed\n", __func__); + return -EINVAL; + } + + /* set initial i2csegctl value */ + writel(i2csegctl_val, &gcr->i2csegctl); + + /* enable SMB module */ + setbits_8(®->ctl2, SMBCTL2_ENABLE); + + /* select register bank 0 */ + clrbits_8(®->ctl3, SMBCTL3_BNK_SEL); + + /* single byte mode */ + clrbits_8(®->bank0.fif_ctl, SMBFIF_CTL_FIFO_EN); + + /* set POLL mode */ + writeb(0, ®->ctl1); + + printf("I2C bus %d ready. speed=%d, base=0x%x, apb=%u\n", + bus->num, bus->freq, (u32)(uintptr_t)bus->reg, bus->apb_clk); + + return 0; +} + +static const struct dm_i2c_ops nuvoton_i2c_ops = { + .xfer = npcm_i2c_xfer, + .set_bus_speed = npcm_i2c_set_bus_speed, +}; + +static const struct udevice_id nuvoton_i2c_of_match[] = { + { .compatible = "nuvoton,npcm845-i2c", .data = NPCM8XX_I2CSEGCTL_INIT_VAL}, + { .compatible = "nuvoton,npcm750-i2c", .data = NPCM7XX_I2CSEGCTL_INIT_VAL}, + {} +}; + +U_BOOT_DRIVER(npcm_i2c_bus) = { + .name = "npcm-i2c", + .id = UCLASS_I2C, + .of_match = nuvoton_i2c_of_match, + .probe = npcm_i2c_probe, + .priv_auto = sizeof(struct npcm_i2c_bus), + .ops = &nuvoton_i2c_ops, +}; From 49f3a42edf097fbaca76aef9bfcd98d871b442cb Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Thu, 7 Jul 2022 15:12:17 +0200 Subject: [PATCH 3/3] i2c: avoid dynamic stack use in dm_i2c_write The size of the dynamic stack allocation here is bounded by the if() statement. However, just allocating the maximum size up-front and doing malloc() if necessary avoids code duplication (the i2c_setup_offset() until the invocation of ->xfer), and generates much better (smaller) code: bloat-o-meter drivers/i2c/i2c-uclass.o.{0,1} add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-144 (-144) Function old new delta dm_i2c_write 552 408 -144 Total: Before=3828, After=3684, chg -3.76% It also makes static analysis of maximum stack usage (using the .su files that are automatically generated during build) easier if there are no lines saying "dynamic". [This is not entirely equivalent to the existing code; this now uses the stack for len <= 64 rather than len <= 63, but that seems like a more natural limit.] Signed-off-by: Rasmus Villemoes Reviewed-by: Heiko Schocher --- drivers/i2c/i2c-uclass.c | 32 +++++++++++++------------------- 1 file changed, 13 insertions(+), 19 deletions(-) diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c index 335911c46bb..8d9a89ed890 100644 --- a/drivers/i2c/i2c-uclass.c +++ b/drivers/i2c/i2c-uclass.c @@ -168,6 +168,9 @@ int dm_i2c_write(struct udevice *dev, uint offset, const uint8_t *buffer, struct udevice *bus = dev_get_parent(dev); struct dm_i2c_ops *ops = i2c_get_ops(bus); struct i2c_msg msg[1]; + uint8_t _buf[I2C_MAX_OFFSET_LEN + 64]; + uint8_t *buf = _buf; + int ret; if (!ops->xfer) return -ENOSYS; @@ -192,29 +195,20 @@ int dm_i2c_write(struct udevice *dev, uint offset, const uint8_t *buffer, * need to allow space for the offset (up to 4 bytes) and the message * itself. */ - if (len < 64) { - uint8_t buf[I2C_MAX_OFFSET_LEN + len]; - - i2c_setup_offset(chip, offset, buf, msg); - msg->len += len; - memcpy(buf + chip->offset_len, buffer, len); - - return ops->xfer(bus, msg, 1); - } else { - uint8_t *buf; - int ret; - + if (len > sizeof(_buf) - I2C_MAX_OFFSET_LEN) { buf = malloc(I2C_MAX_OFFSET_LEN + len); if (!buf) return -ENOMEM; - i2c_setup_offset(chip, offset, buf, msg); - msg->len += len; - memcpy(buf + chip->offset_len, buffer, len); - - ret = ops->xfer(bus, msg, 1); - free(buf); - return ret; } + + i2c_setup_offset(chip, offset, buf, msg); + msg->len += len; + memcpy(buf + chip->offset_len, buffer, len); + + ret = ops->xfer(bus, msg, 1); + if (buf != _buf) + free(buf); + return ret; } int dm_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)