[PATCH] i2c-axxia: support slave mode
From: Adamski, Krzysztof (Nokia - PL/Wroclaw)
Date: Thu Aug 01 2019 - 09:21:51 EST
This device contains both master and slave controllers which can be
enabled simultaneously. Both controllers share the same SDA/SCL lines
and interrupt source but has separate control and status registers.
Controllers also works in loopback mode - slave device can communicate
with its own master controller internally. The controller can handle up
to two addresses, both of which may be 10 bit. Most of the logic
(sending (N)ACK, handling repeated start or switching between
write/read) is handled automatically which makes working with this
controller quite easy.
For simplicity, this patch adds basic support, limiting to only one
slave address. Support for the 2nd device may be added in the future.
Note that synchronize_irq() is used to ensure any running slave interrupt
is finished to make sure slave i2c_client structure can be safely used
by i2c_slave_event.
Signed-off-by: Krzysztof Adamski <krzysztof.adamski@xxxxxxxxx>
---
Note that checkpatch shows warnings about "line over 80 characters" for
some of those register definitions added but I personally think
splitting those comments would decrease readability, not increase it. I
can do that, however, if you think otherwise.
---
drivers/i2c/busses/Kconfig | 1 +
drivers/i2c/busses/i2c-axxia.c | 160 +++++++++++++++++++++++++++++++--
2 files changed, 153 insertions(+), 8 deletions(-)
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 09367fc014c3..3e1d196fce2e 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -429,6 +429,7 @@ config I2C_AXXIA
tristate "Axxia I2C controller"
depends on ARCH_AXXIA || COMPILE_TEST
default ARCH_AXXIA
+ select I2C_SLAVE
help
Say yes if you want to support the I2C bus on Axxia platforms.
diff --git a/drivers/i2c/busses/i2c-axxia.c b/drivers/i2c/busses/i2c-axxia.c
index ff3142b15cab..9095b9cf5963 100644
--- a/drivers/i2c/busses/i2c-axxia.c
+++ b/drivers/i2c/busses/i2c-axxia.c
@@ -77,6 +77,40 @@
MST_STATUS_IP)
#define MST_TX_BYTES_XFRD 0x50
#define MST_RX_BYTES_XFRD 0x54
+#define SLV_ADDR_DEC_CTL 0x58
+#define SLV_ADDR_DEC_GCE BIT(0) /* ACK to General Call Address from own master (loopback) */
+#define SLV_ADDR_DEC_OGCE BIT(1) /* ACK to General Call Address from external masters */
+#define SLV_ADDR_DEC_SA1E BIT(2) /* ACK to addr_1 enabled */
+#define SLV_ADDR_DEC_SA1M BIT(3) /* 10-bit addressing for addr_1 enabled */
+#define SLV_ADDR_DEC_SA2E BIT(4) /* ACK to addr_2 enabled */
+#define SLV_ADDR_DEC_SA2M BIT(5) /* 10-bit addressing for addr_2 enabled */
+#define SLV_ADDR_1 0x5c
+#define SLV_ADDR_2 0x60
+#define SLV_RX_CTL 0x64
+#define SLV_RX_ACSA1 BIT(0) /* Generate ACK for writes to addr_1 */
+#define SLV_RX_ACSA2 BIT(1) /* Generate ACK for writes to addr_2 */
+#define SLV_RX_ACGCA BIT(2) /* ACK data phase transfers to General Call Address */
+#define SLV_DATA 0x68
+#define SLV_RX_FIFO 0x6c
+#define SLV_FIFO_DV1 BIT(0) /* Data Valid for addr_1 */
+#define SLV_FIFO_DV2 BIT(1) /* Data Valid for addr_2 */
+#define SLV_FIFO_AS BIT(2) /* (N)ACK Sent */
+#define SLV_FIFO_TNAK BIT(3) /* Timeout NACK */
+#define SLV_FIFO_STRC BIT(4) /* First byte after start condition received */
+#define SLV_FIFO_RSC BIT(5) /* Repeated Start Condition */
+#define SLV_FIFO_STPC BIT(6) /* Stop Condition */
+#define SLV_FIFO_DV (SLV_FIFO_DV1 | SLV_FIFO_DV2)
+#define SLV_INT_ENABLE 0x70
+#define SLV_INT_STATUS 0x74
+#define SLV_STATUS_RFH BIT(0) /* FIFO service */
+#define SLV_STATUS_WTC BIT(1) /* Write transfer complete */
+#define SLV_STATUS_SRS1 BIT(2) /* Slave read from addr 1 */
+#define SLV_STATUS_SRRS1 BIT(3) /* Repeated start from addr 1 */
+#define SLV_STATUS_SRND1 BIT(4) /* Read request not following start condition */
+#define SLV_STATUS_SRC1 BIT(5) /* Read canceled */
+#define SLV_STATUS_SRAT1 BIT(6) /* Slave Read timed out */
+#define SLV_STATUS_SRDRE1 BIT(7) /* Data written after timed out */
+#define SLV_READ_DUMMY 0x78
#define SCL_HIGH_PERIOD 0x80
#define SCL_LOW_PERIOD 0x84
#define SPIKE_FLTR_LEN 0x88
@@ -111,6 +145,8 @@ struct axxia_i2c_dev {
struct clk *i2c_clk;
u32 bus_clk_rate;
bool last;
+ struct i2c_client *slave;
+ int irq;
};
static void i2c_int_disable(struct axxia_i2c_dev *idev, u32 mask)
@@ -276,13 +312,73 @@ static int axxia_i2c_fill_tx_fifo(struct axxia_i2c_dev *idev)
return ret;
}
+static void axxia_i2c_slv_fifo_event(struct axxia_i2c_dev *idev)
+{
+ u32 fifo_status = readl(idev->base + SLV_RX_FIFO);
+ struct device *dev = idev->dev;
+ u8 val;
+
+ if (fifo_status & SLV_FIFO_DV1) {
+ if (fifo_status & SLV_FIFO_STRC) {
+ dev_dbg(dev, "First data byte sent\n");
+ i2c_slave_event(idev->slave,
+ I2C_SLAVE_WRITE_REQUESTED, &val);
+ }
+
+ val = readl(idev->base + SLV_DATA);
+ dev_dbg(dev, "Received byte - 0x%x\n", val);
+ i2c_slave_event(idev->slave, I2C_SLAVE_WRITE_RECEIVED, &val);
+ }
+ if (fifo_status & SLV_FIFO_STPC) {
+ dev_dbg(dev, "Stop condition received\n");
+ readl(idev->base + SLV_DATA); /* dummy read */
+ i2c_slave_event(idev->slave, I2C_SLAVE_STOP, &val);
+ }
+ if (fifo_status & SLV_FIFO_RSC) {
+ dev_dbg(dev, "Receved byte after repeated start\n");
+ readl(idev->base + SLV_DATA); /* dummy read */
+ }
+}
+
+static irqreturn_t axxia_i2c_slv_isr(struct axxia_i2c_dev *idev)
+{
+ u32 status = readl(idev->base + SLV_INT_STATUS);
+ u8 val;
+
+ if (status & SLV_STATUS_RFH)
+ axxia_i2c_slv_fifo_event(idev);
+ if (status & SLV_STATUS_SRS1) {
+ i2c_slave_event(idev->slave, I2C_SLAVE_READ_REQUESTED, &val);
+ dev_dbg(idev->dev, "First byte requested RS=%d, response=%x\n",
+ !!(status & SLV_STATUS_SRRS1), val);
+ writel(val, idev->base + SLV_DATA);
+ }
+ if (status & SLV_STATUS_SRND1) {
+ dev_dbg(idev->dev, "Read request not after start condition\n");
+ i2c_slave_event(idev->slave, I2C_SLAVE_READ_PROCESSED, &val);
+ writel(val, idev->base + SLV_DATA);
+ }
+ if (status & SLV_STATUS_SRC1) {
+ dev_dbg(idev->dev, "Slave read terminated\n");
+ i2c_slave_event(idev->slave, I2C_SLAVE_STOP, &val);
+ }
+
+ writel(INT_SLV, idev->base + INTERRUPT_STATUS);
+ return IRQ_HANDLED;
+}
+
static irqreturn_t axxia_i2c_isr(int irq, void *_dev)
{
struct axxia_i2c_dev *idev = _dev;
+ irqreturn_t ret = IRQ_NONE;
u32 status;
- if (!(readl(idev->base + INTERRUPT_STATUS) & INT_MST))
- return IRQ_NONE;
+ status = readl(idev->base + INTERRUPT_STATUS);
+
+ if (status & INT_SLV)
+ ret = axxia_i2c_slv_isr(idev);
+ if (!(status & INT_MST))
+ return ret;
/* Read interrupt status bits */
status = readl(idev->base + MST_INT_STATUS);
@@ -583,9 +679,58 @@ static u32 axxia_i2c_func(struct i2c_adapter *adap)
return caps;
}
+static int axxia_i2c_reg_slave(struct i2c_client *slave)
+{
+ struct axxia_i2c_dev *idev = i2c_get_adapdata(slave->adapter);
+ u32 slv_int_mask = SLV_STATUS_RFH;
+ u32 dec_ctl;
+
+ if (idev->slave)
+ return -EBUSY;
+
+ idev->slave = slave;
+
+ /* Enable slave mode as well */
+ writel(GLOBAL_MST_EN | GLOBAL_SLV_EN, idev->base + GLOBAL_CONTROL);
+ writel(INT_MST | INT_SLV, idev->base + INTERRUPT_ENABLE);
+
+ /* Set slave address */
+ dec_ctl = SLV_ADDR_DEC_SA1E;
+ if (slave->flags & I2C_CLIENT_TEN)
+ dec_ctl |= SLV_ADDR_DEC_SA1M;
+
+ writel(SLV_RX_ACSA1, idev->base + SLV_RX_CTL);
+ writel(dec_ctl, idev->base + SLV_ADDR_DEC_CTL);
+ writel(slave->addr, idev->base + SLV_ADDR_1);
+
+ /* Enable interrupts */
+ slv_int_mask |= SLV_STATUS_SRS1 | SLV_STATUS_SRRS1 | SLV_STATUS_SRND1;
+ slv_int_mask |= SLV_STATUS_SRC1;
+ writel(slv_int_mask, idev->base + SLV_INT_ENABLE);
+
+ return 0;
+}
+
+static int axxia_i2c_unreg_slave(struct i2c_client *slave)
+{
+ struct axxia_i2c_dev *idev = i2c_get_adapdata(slave->adapter);
+
+ /* Disable slave mode */
+ writel(GLOBAL_MST_EN, idev->base + GLOBAL_CONTROL);
+ writel(INT_MST, idev->base + INTERRUPT_ENABLE);
+
+ synchronize_irq(idev->irq);
+
+ idev->slave = NULL;
+
+ return 0;
+}
+
static const struct i2c_algorithm axxia_i2c_algo = {
.master_xfer = axxia_i2c_xfer,
.functionality = axxia_i2c_func,
+ .reg_slave = axxia_i2c_reg_slave,
+ .unreg_slave = axxia_i2c_unreg_slave,
};
static const struct i2c_adapter_quirks axxia_i2c_quirks = {
@@ -599,7 +744,6 @@ static int axxia_i2c_probe(struct platform_device *pdev)
struct axxia_i2c_dev *idev = NULL;
struct resource *res;
void __iomem *base;
- int irq;
int ret = 0;
idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL);
@@ -611,10 +755,10 @@ static int axxia_i2c_probe(struct platform_device *pdev)
if (IS_ERR(base))
return PTR_ERR(base);
- irq = platform_get_irq(pdev, 0);
- if (irq < 0) {
+ idev->irq = platform_get_irq(pdev, 0);
+ if (idev->irq < 0) {
dev_err(&pdev->dev, "missing interrupt resource\n");
- return irq;
+ return idev->irq;
}
idev->i2c_clk = devm_clk_get(&pdev->dev, "i2c");
@@ -643,10 +787,10 @@ static int axxia_i2c_probe(struct platform_device *pdev)
goto error_disable_clk;
}
- ret = devm_request_irq(&pdev->dev, irq, axxia_i2c_isr, 0,
+ ret = devm_request_irq(&pdev->dev, idev->irq, axxia_i2c_isr, 0,
pdev->name, idev);
if (ret) {
- dev_err(&pdev->dev, "failed to claim IRQ%d\n", irq);
+ dev_err(&pdev->dev, "failed to claim IRQ%d\n", idev->irq);
goto error_disable_clk;
}
--
2.21.0