Hi Max, here is the review:
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index c94db1c..f973632 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -663,6 +663,16 @@ config I2C_PXA_SLAVE
> is necessary for systems where the PXA may be a target on the
> I2C bus.
>
> +config I2C_RK3X
> + tristate "Rockchip RK3xxx I2C adapter"
> + depends on OF
> + help
> + Say Y here to include support for the I2C adapter in Rockchip RK3xxx
> + SoCs.
> +
> + This driver can also be built as a module. If so, the module will
> + be called i2c-rk3x.
> +
Please keep it sorted!
> config I2C_QUP
> tristate "Qualcomm QUP based I2C controller"
> depends on ARCH_QCOM
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 18d18ff..39b6851 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -65,6 +65,7 @@ obj-$(CONFIG_I2C_PNX) += i2c-pnx.o
> obj-$(CONFIG_I2C_PUV3) += i2c-puv3.o
> obj-$(CONFIG_I2C_PXA) += i2c-pxa.o
> obj-$(CONFIG_I2C_PXA_PCI) += i2c-pxa-pci.o
> +obj-$(CONFIG_I2C_RK3X) += i2c-rk3x.o
Please keep it sorted!
> obj-$(CONFIG_I2C_QUP) += i2c-qup.o
> obj-$(CONFIG_I2C_RIIC) += i2c-riic.o
> obj-$(CONFIG_I2C_S3C2410) += i2c-s3c2410.o
> diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
> new file mode 100644
> index 0000000..429983b
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-rk3x.c
> @@ -0,0 +1,742 @@
> +/*
> + * Driver for I2C adapter in Rockchip RK3xxx SoC
> + *
> + * Max Schwarz <max.schw...@online.de>
> + * based on the patches by Rockchip Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
...
> +struct rk3x_i2c {
> + struct i2c_adapter adap;
> + struct device *dev;
> + struct rk3x_i2c_soc_data *soc_data;
> +
> + /* Hardware resources */
> + void __iomem *regs;
> + struct regmap *grf;
No need to store this one here, it is only used in probe.
> + struct clk *clk;
> + int irq;
No need to store this one here, it is only used in probe.
> +
> + /* Settings */
> + unsigned int scl_frequency;
> +
> + /* Synchronization & notification */
> + spinlock_t lock;
Why the lock? The core has per-adapter locks anyhow.
> + wait_queue_head_t wait;
> + bool busy;
> +
> + /* Current message */
> + struct i2c_msg *msg;
> + u8 addr;
> + unsigned int mode;
> +
> + /* I2C state machine */
> + enum rk3x_i2c_state state;
> + unsigned int processed; /* sent/received bytes */
> + int error;
> +};
> +
> +static inline void i2c_writel(struct rk3x_i2c *i2c, u32 value,
> + unsigned int offset)
> +{
> + writel(value, i2c->regs + offset);
> +}
> +
> +static inline u32 i2c_readl(struct rk3x_i2c *i2c, unsigned int offset)
> +{
> + return readl(i2c->regs + offset);
> +}
> +
> +/* Reset all interrupt pending bits */
> +static inline void rk3x_i2c_clean_ipd(struct rk3x_i2c *i2c)
> +{
> + i2c_writel(i2c, REG_INT_ALL, REG_IPD);
> +}
In my book, such functions are a bit on the superfluous side, yet no
reason to change.
> +/**
> + * Setup a read according to i2c->msg
> + */
> +static void rk3x_i2c_prepare_read(struct rk3x_i2c *i2c)
> +{
> + unsigned int len = i2c->msg->len - i2c->processed;
> + u32 con;
> +
> + con = i2c_readl(i2c, REG_CON);
> +
> + /* the hw can read up to 32 bytes at a time. If we need more than one
> + * chunk, send an ACK after the last byte of the current chunk. */
Check CodingStyle for multiline comments.
> + if (unlikely(len > 32)) {
> + len = 32;
> + con &= ~REG_CON_LASTACK;
> + } else {
> + con |= REG_CON_LASTACK;
> + }
> +
> + /* make sure we are in plain RX mode if we read a second chunk */
> + if (i2c->processed != 0) {
> + con &= ~REG_CON_MOD_MASK;
> + con |= REG_CON_MOD(REG_CON_MOD_RX);
> + }
> +
> + i2c_writel(i2c, con, REG_CON);
> + i2c_writel(i2c, len, REG_MRXCNT);
> +}
> +
> +/**
> + * Fill the transmit buffer with data from i2c->msg
> + */
> +static void rk3x_i2c_fill_transmit_buf(struct rk3x_i2c *i2c)
> +{
> + unsigned int i, j;
> + u32 cnt = 0;
> + u32 val;
> + u8 byte;
> +
> + for (i = 0; i < 8; ++i) {
> + val = 0;
> + for (j = 0; j < 4; ++j) {
> + if (i2c->processed == i2c->msg->len)
> + break;
> +
> + if (i2c->processed == 0 && cnt == 0)
> + byte = (i2c->addr & 0x7f) << 1;
> + else
> + byte = i2c->msg->buf[i2c->processed++];
> +
> + val |= byte << (j*8);
Space around operators.
> + cnt++;
> + }
> +
> + i2c_writel(i2c, val, TXBUFFER_BASE + 4*i);
Ditto.
> +
> + if (i2c->processed == i2c->msg->len)
> + break;
> + }
> +
> + i2c_writel(i2c, cnt, REG_MTXCNT);
> +}
> +
> +
> +/* IRQ handlers for individual states */
> +
> +static void rk3x_i2c_handle_start(struct rk3x_i2c *i2c, unsigned int ipd)
> +{
> + if (!(ipd & REG_INT_START)) {
> + rk3x_i2c_stop(i2c, -ENXIO);
> + dev_warn(i2c->dev, "unexpected irq in START: 0x%x\n", ipd);
> + rk3x_i2c_clean_ipd(i2c);
> + return;
> + }
> +
> + /* ack interrupt */
> + i2c_writel(i2c, REG_INT_START, REG_IPD);
> +
> + /* disable start bit */
> + i2c_writel(i2c, i2c_readl(i2c, REG_CON) & ~REG_CON_START, REG_CON);
> +
> + /* enable appropriate interrupts and transition */
> + if (i2c->mode == REG_CON_MOD_TX) {
> + i2c_writel(i2c, REG_INT_MBTF | REG_INT_NAKRCV, REG_IEN);
> + i2c->state = STATE_WRITE;
> + rk3x_i2c_fill_transmit_buf(i2c);
> + } else {
> + /* in any other case, we are going to be reading. */
> + i2c_writel(i2c, REG_INT_MBRF | REG_INT_NAKRCV, REG_IEN);
> + i2c->state = STATE_READ;
> + rk3x_i2c_prepare_read(i2c);
> + }
> +}
> +
> +static void rk3x_i2c_handle_write(struct rk3x_i2c *i2c, unsigned int ipd)
> +{
> + if (!(ipd & REG_INT_MBTF)) {
> + rk3x_i2c_stop(i2c, -ENXIO);
> + dev_err(i2c->dev, "unexpected irq in WRITE: 0x%x\n", ipd);
> + rk3x_i2c_clean_ipd(i2c);
> + return;
> + }
> +
> + /* ack interrupt */
> + i2c_writel(i2c, REG_INT_MBTF, REG_IPD);
> +
> + /* are we finished? */
> + if (i2c->processed == i2c->msg->len)
> + rk3x_i2c_stop(i2c, i2c->error);
> + else
> + rk3x_i2c_fill_transmit_buf(i2c);
It looks to me that you STOP after every message? You should use
REPEATED_START inbetween messages and only stop after the last message
of a transfer.
> +}
> +
> +static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd)
> +{
> + unsigned int i;
> + unsigned int len = i2c->msg->len - i2c->processed;
> + unsigned int val;
> + u8 byte;
> +
> + /* we only care for MBRF here. */
> + if (!(ipd & REG_INT_MBRF))
> + return;
> +
> + /* ack interrupt */
> + i2c_writel(i2c, REG_INT_MBRF, REG_IPD);
> +
> + /* read the data from receive buffer */
> + for (i = 0; i < len; ++i) {
> + if (i % 4 == 0)
> + val = i2c_readl(i2c, RXBUFFER_BASE + (i / 4) * 4);
> +
> + byte = (val >> ((i % 4) * 8)) & 0xff;
> + i2c->msg->buf[i2c->processed++] = byte;
> + }
> +
> + /* are we finished? */
> + if (i2c->processed == i2c->msg->len)
> + rk3x_i2c_stop(i2c, i2c->error);
> + else
> + rk3x_i2c_prepare_read(i2c);
Ditto.
> +}
> +
> +static void rk3x_i2c_handle_stop(struct rk3x_i2c *i2c, unsigned int ipd)
> +{
> + unsigned int con;
> +
> + if (!(ipd & REG_INT_STOP)) {
> + rk3x_i2c_stop(i2c, -ENXIO);
> + dev_err(i2c->dev, "unexpected irq in STOP: 0x%x\n", ipd);
> + rk3x_i2c_clean_ipd(i2c);
> + return;
> + }
> +
> + /* ack interrupt */
> + i2c_writel(i2c, REG_INT_STOP, REG_IPD);
> +
> + /* disable STOP bit */
> + con = i2c_readl(i2c, REG_CON);
> + con &= ~REG_CON_STOP;
> + i2c_writel(i2c, con, REG_CON);
> +
> + i2c->busy = 0;
> + i2c->state = STATE_IDLE;
> +
> + /* signal rk3x_i2c_xfer that we are finished */
> + wake_up(&i2c->wait);
> +}
> +
> +static irqreturn_t rk3x_i2c_irq(int irqno, void *dev_id)
> +{
> + struct rk3x_i2c *i2c = dev_id;
> + unsigned int ipd;
> +
> + spin_lock(&i2c->lock);
> +
> + ipd = i2c_readl(i2c, REG_IPD);
> + if (i2c->state == STATE_IDLE) {
> + dev_warn(i2c->dev, "irq in STATE_IDLE, ipd = 0x%x\n", ipd);
> + rk3x_i2c_clean_ipd(i2c);
> + goto out;
> + }
> +
> + dev_dbg(i2c->dev, "IRQ: state %d, ipd: %x\n", i2c->state, ipd);
> +
> + /* Clean interrupt bits we don't care about */
> + ipd &= ~(REG_INT_BRF | REG_INT_BTF);
> +
> + if (ipd & REG_INT_NAKRCV) {
> + /* We got a NACK in the last operation. Depending on whether
> + * IGNORE_NAK is set, we have to stop the operation and report
> + * an error. */
> + i2c_writel(i2c, REG_INT_NAKRCV, REG_IPD);
> +
> + ipd &= ~REG_INT_NAKRCV;
> +
> + if (!(i2c->msg->flags & I2C_M_IGNORE_NAK))
> + rk3x_i2c_stop(i2c, -EAGAIN);
NACK is -ENXIO. -EAGAIN is arbitration lost. Check
Documentation/i2c/fault-codes (and probably revisit the other error
codes, too. I might have missed some).
> + }
> +
> + /* is there anything left to handle? */
> + if (unlikely(ipd == 0))
> + goto out;
> +
> + switch (i2c->state) {
> + case STATE_START:
> + rk3x_i2c_handle_start(i2c, ipd);
> + break;
> + case STATE_WRITE:
> + rk3x_i2c_handle_write(i2c, ipd);
> + break;
> + case STATE_READ:
> + rk3x_i2c_handle_read(i2c, ipd);
> + break;
> + case STATE_STOP:
> + rk3x_i2c_handle_stop(i2c, ipd);
> + break;
> + case STATE_IDLE:
> + break;
> + }
> +
> +out:
> + spin_unlock(&i2c->lock);
> + return IRQ_HANDLED;
> +}
> +
> +static void rk3x_i2c_set_scl_rate(struct rk3x_i2c *i2c, unsigned long
> scl_rate)
> +{
> + unsigned long i2c_rate = clk_get_rate(i2c->clk);
> + unsigned int div;
> +
> + /* SCL rate = (clk rate) / (8 * DIV) */
> + div = DIV_ROUND_UP(i2c_rate, scl_rate * 8);
> +
> + /* The lower and upper half of the CLKDIV reg describe the length of
> + * SCL low & high periods. */
> + div = DIV_ROUND_UP(div, 2);
> +
> + i2c_writel(i2c, (div << 16) | (div & 0xffff), REG_CLKDIV);
> +}
> +
> +/**
> + * Setup I2C registers for an I2C operation specified by msgs, num.
> + *
> + * Must be called with i2c->lock held.
> + *
> + * @msgs: I2C msgs to process
> + * @num: Number of msgs
> + *
> + * returns: Number of I2C msgs processed or negative in case of error
> + */
> +static int rk3x_i2c_setup(struct rk3x_i2c *i2c, struct i2c_msg *msgs, int
> num)
> +{
> + u32 addr = (msgs[0].addr & 0x7f) << 1;
> + int ret = 0;
> +
> + /*
> + * The I2C adapter can issue a small (len < 4) write packet before
> + * reading. This speeds up SMBus-style register reads.
> + * The MRXADDR/MRXRADDR hold the slave address and the slave register
> + * address in this case.
> + */
> +
> + if (num >= 2 && msgs[0].len < 4
> + && !(msgs[0].flags & I2C_M_RD)
> + && (msgs[1].flags & I2C_M_RD)) {
> + u32 reg_addr = 0;
> +
> + dev_dbg(i2c->dev, "Combined write/read from addr 0x%x\n",
> + addr >> 1);
> +
> + if (msgs[0].len == 0)
> + return -EINVAL;
Can the controller do SMBUS_QUICK (len == 0) in general? For the case it
cannot do it only in this multi-packet mode, then you should fall back
to the "boring" mode.
> +
> + /* Fill MRXRADDR with the register address(es) */
> + reg_addr = msgs[0].buf[0];
> + reg_addr |= REG_MRXADDR_LOW;
> +
> + if (msgs[0].len >= 2) {
> + reg_addr |= msgs[0].buf[1] << 8;
> + reg_addr |= REG_MRXADDR_MID;
> +
> + if (msgs[0].len >= 3) {
> + reg_addr |= msgs[0].buf[2] << 16;
> + reg_addr |= REG_MRXADDR_HIGH;
> + }
> + }
> +
> + /* msgs[0] is handled by hw. */
> + i2c->msg = &msgs[1];
> +
> + i2c->mode = REG_CON_MOD_REGISTER_TX;
> +
> + i2c_writel(i2c, addr | REG_MRXADDR_LOW, REG_MRXADDR);
> + i2c_writel(i2c, reg_addr, REG_MRXRADDR);
> +
> + ret = 2;
> + } else {
> + /* We'll have to do it the boring way and process the msgs
> + * one-by-one. */
> +
> + if (msgs[0].flags & I2C_M_RD) {
> + addr |= 1; /* set read bit */
> +
> + /* We have to transmit the slave addr first. Use
> + * MOD_REGISTER_TX for that purpose. */
> + i2c->mode = REG_CON_MOD_REGISTER_TX;
> + i2c_writel(i2c, addr | REG_MRXADDR_LOW, REG_MRXADDR);
> + i2c_writel(i2c, 0, REG_MRXRADDR);
> + } else {
> + i2c->mode = REG_CON_MOD_TX;
> + }
> +
> + i2c->msg = &msgs[0];
> +
> + ret = 1;
> + }
> +
> + i2c->addr = msgs[0].addr;
> + i2c->busy = true;
> + i2c->state = STATE_START;
> + i2c->processed = 0;
> + i2c->error = 0;
> +
> + rk3x_i2c_clean_ipd(i2c);
> +
> + return ret;
> +}
> +
> +static int rk3x_i2c_xfer(struct i2c_adapter *adap,
> + struct i2c_msg *msgs, int num)
> +{
> + struct rk3x_i2c *i2c = (struct rk3x_i2c *)adap->algo_data;
> + unsigned long timeout, flags;
> + int ret = 0;
> + int i;
> +
> + spin_lock_irqsave(&i2c->lock, flags);
> +
> + clk_enable(i2c->clk);
> +
> + /* The clock rate might have changed, so setup the divider again */
> + rk3x_i2c_set_scl_rate(i2c, i2c->scl_frequency);
> +
> + /* Process msgs. We can handle more than one message at once (see
> + * rk3x_i2c_setup()). */
> + for (i = 0; i < num; i += ret) {
> + ret = rk3x_i2c_setup(i2c, msgs + i, num);
> +
> + if (ret < 0) {
> + dev_err(i2c->dev, "rk3x_i2c_setup() failed\n");
> + break;
> + }
> +
> + spin_unlock_irqrestore(&i2c->lock, flags);
> +
> + rk3x_i2c_start(i2c);
> +
> + timeout = wait_event_timeout(i2c->wait, !i2c->busy,
> + msecs_to_jiffies(WAIT_TIMEOUT));
> +
> + spin_lock_irqsave(&i2c->lock, flags);
> +
> + if (timeout == 0) {
> + dev_err(i2c->dev, "timeout, ipd: 0x%08X",
> + i2c_readl(i2c, REG_IPD));
> +
> + /* Force a STOP condition without interrupt */
> + i2c_writel(i2c, 0, REG_IEN);
> + i2c_writel(i2c, REG_CON_EN | REG_CON_STOP, REG_CON);
> +
> + i2c->state = STATE_IDLE;
> +
> + ret = -ETIMEDOUT;
> + break;
> + }
> +
> + if (i2c->error) {
> + ret = i2c->error;
> + break;
> + }
> + }
> +
> + clk_disable(i2c->clk);
> + spin_unlock_irqrestore(&i2c->lock, flags);
> +
> + return ret;
> +}
> +
> +static u32 rk3x_i2c_func(struct i2c_adapter *adap)
> +{
> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
> +}
> +
> +static const struct i2c_algorithm rk3x_i2c_algorithm = {
> + .master_xfer = rk3x_i2c_xfer,
> + .functionality = rk3x_i2c_func,
> +};
> +
> +static const struct of_device_id rk3x_i2c_match[];
? Why don't you move the complete table here?
> +
> +static int rk3x_i2c_probe(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + const struct of_device_id *match;
> + struct rk3x_i2c *i2c;
> + struct resource *mem;
> + int ret = 0;
> + u32 value;
> +
> + if (!pdev->dev.of_node) {
> + dev_err(&pdev->dev, "rk3x-i2c needs a devicetree node\n");
> + return -EINVAL;
> + }
Is the platform DT only? Then, the above check is superfluous since
probe wouldn't be called without a match.
> +
> + i2c = devm_kzalloc(&pdev->dev, sizeof(struct rk3x_i2c), GFP_KERNEL);
> + if (!i2c)
> + return -ENOMEM;
> +
> + match = of_match_node(rk3x_i2c_match, np);
> + i2c->soc_data = (struct rk3x_i2c_soc_data *)match->data;
> +
> + if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
> + &i2c->scl_frequency)) {
> + i2c->scl_frequency = 100 * 1000;
> + dev_info(&pdev->dev, "using default SCL frequency: 100kHz\n");
> + }
Shouldn't there be a sanity check for the value of "clock-frequency"?
> + strlcpy(i2c->adap.name, "rk3x-i2c", sizeof(i2c->adap.name));
> + i2c->adap.owner = THIS_MODULE;
> + i2c->adap.algo = &rk3x_i2c_algorithm;
> + i2c->adap.retries = 3;
> + i2c->adap.dev.of_node = np;
> + i2c->adap.algo_data = i2c;
> + i2c->adap.dev.parent = &pdev->dev;
> +
> + i2c->dev = &pdev->dev;
> +
> + spin_lock_init(&i2c->lock);
> + init_waitqueue_head(&i2c->wait);
> +
> + i2c->clk = devm_clk_get(&pdev->dev, 0);
> + if (IS_ERR(i2c->clk)) {
> + dev_err(&pdev->dev, "cannot get clock\n");
> + return PTR_ERR(i2c->clk);
> + }
> +
> + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
> + if (IS_ERR(i2c->regs))
> + return PTR_ERR(i2c->regs);
> +
> + /* Try to set the I2C adapter number from dt */
> + i2c->adap.nr = of_alias_get_id(np, "i2c");
> + if (i2c->adap.nr < 0)
> + i2c->adap.nr = -1; /* request dynamic ID */
The core does alias handling. Just call i2c_add_adapter().
You will probably need the number in a local variable, though
> +
> + /* Switch to new interface if the SoC also offers the old one.
> + * The control bit is located in the GRF register space. */
> + if (i2c->soc_data->grf_offset >= 0) {
> + i2c->grf = syscon_regmap_lookup_by_phandle(np, "rockchip,grf");
> + if (IS_ERR(i2c->grf)) {
> + dev_err(&pdev->dev,
> + "rk3x-i2c needs 'rockchip,grf' property\n");
> + return PTR_ERR(i2c->grf);
> + }
> +
> + if (i2c->adap.nr < 0) {
> + dev_err(&pdev->dev, "rk3x-i2c needs i2cX alias");
> + return -EINVAL;
> + }
> +
> + /* 27+i: write mask, 11+i: value */
> + value = BIT(27 + i2c->adap.nr) | BIT(11 + i2c->adap.nr);
> +
> + ret = regmap_write(i2c->grf, i2c->soc_data->grf_offset, value);
> + if (ret != 0) {
> + dev_err(i2c->dev, "Could not write to GRF: %d\n", ret);
> + return ret;
> + }
> + }
> +
> + /* IRQ setup */
> + i2c->irq = platform_get_irq(pdev, 0);
> + if (i2c->irq < 0) {
> + dev_err(&pdev->dev, "cannot find rk3x IRQ\n");
> + return i2c->irq;
> + }
> +
> + ret = devm_request_irq(&pdev->dev, i2c->irq, rk3x_i2c_irq,
> + 0, dev_name(&pdev->dev), i2c);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "cannot request IRQ\n");
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, i2c);
> +
> + ret = clk_prepare(i2c->clk);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "Could not prepare clock\n");
> + return ret;
> + }
> +
> + ret = i2c_add_numbered_adapter(&i2c->adap);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "Could not register adapter\n");
> + goto err_clk;
> + }
> +
> + dev_info(&pdev->dev, "Initialized RK3xxx I2C bus at 0x%08x\n",
> + (unsigned int)i2c->regs);
> +
> + return 0;
> +
> +err_clk:
> + clk_unprepare(i2c->clk);
> + return ret;
> +}
Thanks,
Wolfram
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