Re: [PATCH v3 5/6] i2c: Add Actions Semiconductor Owl family S900 I2C driver
From: Peter Rosin
Date: Sun Jul 01 2018 - 01:03:52 EST
On June 30, 2018 3:33:29 PM GMT+02:00, Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> wrote:
>Add Actions Semiconductor Owl family S900 I2C driver.
>
>Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
>---
> drivers/i2c/busses/Kconfig | 7 +
> drivers/i2c/busses/Makefile | 1 +
> drivers/i2c/busses/i2c-owl.c | 477 +++++++++++++++++++++++++++++++++++
> 3 files changed, 485 insertions(+)
> create mode 100644 drivers/i2c/busses/i2c-owl.c
>
>diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>index 4f8df2ec87b1..8c8025f87ce4 100644
>--- a/drivers/i2c/busses/Kconfig
>+++ b/drivers/i2c/busses/Kconfig
>@@ -762,6 +762,13 @@ config I2C_OMAP
> Like OMAP1510/1610/1710/5912 and OMAP242x.
> For details see http://www.ti.com/omap.
>
>+config I2C_OWL
>+ tristate "Actions Semiconductor Owl I2C Controller"
>+ depends on ARCH_ACTIONS || COMPILE_TEST
>+ help
>+ Say Y here if you want to use the I2C bus controller on
>+ the Actions Semiconductor Owl SoC's.
>+
> config I2C_PASEMI
> tristate "PA Semi SMBus interface"
> depends on PPC_PASEMI && PCI
>diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
>index 5a869144a0c5..b71618f77880 100644
>--- a/drivers/i2c/busses/Makefile
>+++ b/drivers/i2c/busses/Makefile
>@@ -76,6 +76,7 @@ obj-$(CONFIG_I2C_MXS) += i2c-mxs.o
> obj-$(CONFIG_I2C_NOMADIK) += i2c-nomadik.o
> obj-$(CONFIG_I2C_OCORES) += i2c-ocores.o
> obj-$(CONFIG_I2C_OMAP) += i2c-omap.o
>+obj-$(CONFIG_I2C_OWL) += i2c-owl.o
> obj-$(CONFIG_I2C_PASEMI) += i2c-pasemi.o
> obj-$(CONFIG_I2C_PCA_PLATFORM) += i2c-pca-platform.o
> obj-$(CONFIG_I2C_PMCMSP) += i2c-pmcmsp.o
>diff --git a/drivers/i2c/busses/i2c-owl.c
>b/drivers/i2c/busses/i2c-owl.c
>new file mode 100644
>index 000000000000..144a249bf994
>--- /dev/null
>+++ b/drivers/i2c/busses/i2c-owl.c
>@@ -0,0 +1,477 @@
>+// SPDX-License-Identifier: GPL-2.0+
>+/*
>+ * Actions Semiconductor Owl SoC's I2C driver
>+ *
>+ * Copyright (c) 2014 Actions Semi Inc.
>+ * Author: David Liu <liuwei@xxxxxxxxxxxxxxxx>
>+ *
>+ * Copyright (c) 2018 Linaro Ltd.
>+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
>+ */
>+
>+#include <linux/clk.h>
>+#include <linux/delay.h>
>+#include <linux/i2c.h>
>+#include <linux/interrupt.h>
>+#include <linux/io.h>
>+#include <linux/module.h>
>+#include <linux/of_device.h>
>+
>+/* I2C registers */
>+#define OWL_I2C_REG_CTL 0x0000
>+#define OWL_I2C_REG_CLKDIV 0x0004
>+#define OWL_I2C_REG_STAT 0x0008
>+#define OWL_I2C_REG_ADDR 0x000C
>+#define OWL_I2C_REG_TXDAT 0x0010
>+#define OWL_I2C_REG_RXDAT 0x0014
>+#define OWL_I2C_REG_CMD 0x0018
>+#define OWL_I2C_REG_FIFOCTL 0x001C
>+#define OWL_I2C_REG_FIFOSTAT 0x0020
>+#define OWL_I2C_REG_DATCNT 0x0024
>+#define OWL_I2C_REG_RCNT 0x0028
>+
>+/* I2Cx_CTL Bit Mask */
>+#define OWL_I2C_CTL_RB BIT(1)
>+#define OWL_I2C_CTL_GBCC(x) (((x) & 0x3) << 2)
>+#define OWL_I2C_CTL_GBCC_NONE OWL_I2C_CTL_GBCC(0)
>+#define OWL_I2C_CTL_GBCC_START OWL_I2C_CTL_GBCC(1)
>+#define OWL_I2C_CTL_GBCC_STOP OWL_I2C_CTL_GBCC(2)
>+#define OWL_I2C_CTL_GBCC_RSTART OWL_I2C_CTL_GBCC(3)
>+#define OWL_I2C_CTL_IRQE BIT(5)
>+#define OWL_I2C_CTL_EN BIT(7)
>+#define OWL_I2C_CTL_AE BIT(8)
>+#define OWL_I2C_CTL_SHSM BIT(10)
>+
>+#define OWL_I2C_DIV_FACTOR(x) ((x) & 0xff)
>+
>+/* I2Cx_STAT Bit Mask */
>+#define OWL_I2C_STAT_RACK BIT(0)
>+#define OWL_I2C_STAT_BEB BIT(1)
>+#define OWL_I2C_STAT_IRQP BIT(2)
>+#define OWL_I2C_STAT_LAB BIT(3)
>+#define OWL_I2C_STAT_STPD BIT(4)
>+#define OWL_I2C_STAT_STAD BIT(5)
>+#define OWL_I2C_STAT_BBB BIT(6)
>+#define OWL_I2C_STAT_TCB BIT(7)
>+#define OWL_I2C_STAT_LBST BIT(8)
>+#define OWL_I2C_STAT_SAMB BIT(9)
>+#define OWL_I2C_STAT_SRGC BIT(10)
>+
>+/* I2Cx_CMD Bit Mask */
>+#define OWL_I2C_CMD_SBE BIT(0)
>+#define OWL_I2C_CMD_RBE BIT(4)
>+#define OWL_I2C_CMD_DE BIT(8)
>+#define OWL_I2C_CMD_NS BIT(9)
>+#define OWL_I2C_CMD_SE BIT(10)
>+#define OWL_I2C_CMD_MSS BIT(11)
>+#define OWL_I2C_CMD_WRS BIT(12)
>+#define OWL_I2C_CMD_SECL BIT(15)
>+
>+#define OWL_I2C_CMD_AS(x) (((x) & 0x7) << 1)
>+#define OWL_I2C_CMD_SAS(x) (((x) & 0x7) << 5)
>+
>+/* I2Cx_FIFOCTL Bit Mask */
>+#define OWL_I2C_FIFOCTL_NIB BIT(0)
>+#define OWL_I2C_FIFOCTL_RFR BIT(1)
>+#define OWL_I2C_FIFOCTL_TFR BIT(2)
>+
>+/* I2Cc_FIFOSTAT Bit Mask */
>+#define OWL_I2C_FIFOSTAT_RNB BIT(1)
>+#define OWL_I2C_FIFOSTAT_RFE BIT(2)
>+#define OWL_I2C_FIFOSTAT_TFF BIT(5)
>+#define OWL_I2C_FIFOSTAT_TFD GENMASK(23, 16)
>+#define OWL_I2C_FIFOSTAT_RFD GENMASK(15, 8)
>+
>+/* I2C bus timeout */
>+#define OWL_I2C_TIMEOUT msecs_to_jiffies(4 * 1000)
>+
>+#define OWL_I2C_MAX_RETRIES 50
>+
>+#define OWL_I2C_DEF_SPEED_HZ 100000
>+#define OWL_I2C_MAX_SPEED_HZ 400000
>+
>+struct owl_i2c_dev {
>+ struct i2c_adapter adap;
>+ struct i2c_msg *msg;
>+ struct completion msg_complete;
>+ struct clk *clk;
>+ void __iomem *base;
>+ unsigned long clk_rate;
>+ u32 bus_freq;
>+ u32 msg_ptr;
>+};
>+
>+static void owl_i2c_update_reg(void __iomem *reg, unsigned int val,
>bool state)
>+{
>+ unsigned int regval;
>+
>+ regval = readl(reg);
>+
>+ if (state)
>+ regval |= val;
>+ else
>+ regval &= ~val;
>+
>+ writel(regval, reg);
>+}
>+
>+static int owl_i2c_reset(struct owl_i2c_dev *i2c_dev)
>+{
>+ unsigned int val, timeout = 0;
>+
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
>+ OWL_I2C_CTL_EN, false);
>+ mdelay(1);
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
>+ OWL_I2C_CTL_EN, true);
>+
>+ /* Reset FIFO */
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
>+ OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR,
>+ true);
>+
>+ /* Wait 50ms for FIFO reset complete */
>+ do {
>+ val = readl(i2c_dev->base + OWL_I2C_REG_FIFOCTL);
>+ if (!(val & (OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR)))
>+ break;
>+ mdelay(1);
>+ } while (timeout++ < OWL_I2C_MAX_RETRIES);
>+
>+ if (timeout > OWL_I2C_MAX_RETRIES) {
>+ dev_err(&i2c_dev->adap.dev, "FIFO reset timeout");
>+ return -ETIMEDOUT;
>+ }
>+
>+ /* Clear status registers */
>+ writel(0, i2c_dev->base + OWL_I2C_REG_STAT);
>+
>+ return 0;
>+}
>+
>+static int owl_i2c_set_freq(struct owl_i2c_dev *i2c_dev)
>+{
>+ unsigned int val;
>+
>+ val = (i2c_dev->clk_rate + i2c_dev->bus_freq * 16 - 1) /
>+ (i2c_dev->bus_freq * 16);
>+
>+ /* Set clock divider factor */
>+ writel(OWL_I2C_DIV_FACTOR(val), i2c_dev->base + OWL_I2C_REG_CLKDIV);
>+
>+ return 0;
>+}
>+
>+static int owl_i2c_hw_init(struct owl_i2c_dev *i2c_dev)
>+{
>+ int ret;
>+
>+ /* Reset I2C controller */
>+ ret = owl_i2c_reset(i2c_dev);
>+ if (ret)
>+ return ret;
>+
>+ /* Set bus frequency */
>+ return owl_i2c_set_freq(i2c_dev);
>+}
>+
>+static irqreturn_t owl_i2c_interrupt(int irq, void *_dev)
>+{
>+ struct owl_i2c_dev *i2c_dev = _dev;
>+ struct i2c_msg *msg = i2c_dev->msg;
>+ unsigned int stat, fifostat;
>+
>+ fifostat = readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT);
>+ if (fifostat & OWL_I2C_FIFOSTAT_RNB) {
>+ dev_dbg(&i2c_dev->adap.dev, "received NACK from device");
>+ goto stop;
>+ }
>+
>+ stat = readl(i2c_dev->base + OWL_I2C_REG_STAT);
>+ if (stat & OWL_I2C_STAT_BEB) {
>+ dev_dbg(&i2c_dev->adap.dev, "bus error");
>+ goto stop;
>+ }
>+
>+ /* Handle FIFO read */
>+ if (msg->flags & I2C_M_RD) {
>+ while ((readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
>+ OWL_I2C_FIFOSTAT_RFE) &&
>+ (i2c_dev->msg_ptr < msg->len)) {
>+ msg->buf[i2c_dev->msg_ptr++] = readl(i2c_dev->base +
>+ OWL_I2C_REG_RXDAT);
>+ }
>+ } else {
>+ /* Handle the remaining bytes which were not sent */
>+ while (!(readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
>+ OWL_I2C_FIFOSTAT_TFF) &&
>+ i2c_dev->msg_ptr < msg->len) {
>+ writel(msg->buf[i2c_dev->msg_ptr++], i2c_dev->base +
>+ OWL_I2C_REG_TXDAT);
>+ }
>+ }
>+
>+stop:
>+ /* Clear pending interrupts */
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_STAT,
>+ OWL_I2C_STAT_IRQP, true);
>+
Here is a read-modify-write on ..._REG_STAT from interrupt context...
>+ complete_all(&i2c_dev->msg_complete);
>+
>+ return IRQ_HANDLED;
>+}
>+
>+static u32 owl_i2c_func(struct i2c_adapter *adap)
>+{
>+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
>+}
>+
>+static int owl_i2c_check_bus_busy(struct i2c_adapter *adap)
>+{
>+ struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
>+ unsigned long timeout;
>+ unsigned int val;
>+
>+ /* Check for Arbitration lost */
>+ val = readl(i2c_dev->base + OWL_I2C_REG_STAT);
>+ if (val & OWL_I2C_STAT_LAB) {
>+ val &= ~OWL_I2C_STAT_LAB;
>+ writel(val, i2c_dev->base + OWL_I2C_REG_STAT);
...and here is one from process context.
Can they cross? If not, why? Either use some locking, or add a comment explaining why this is safe.
>+ return -EAGAIN;
>+ }
>+
>+ /* Check for Bus busy */
>+ timeout = jiffies + OWL_I2C_TIMEOUT;
>+ while (readl(i2c_dev->base + OWL_I2C_REG_STAT) & OWL_I2C_STAT_BBB) {
>+ if (time_after(jiffies, timeout)) {
>+ dev_err(&adap->dev, "Bus busy timeout");
>+ return -ETIMEDOUT;
>+ }
>+ }
>+
>+ return 0;
>+}
>+
>+static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct
>i2c_msg *msgs,
>+ int num)
>+{
>+ struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
>+ struct i2c_msg *msg;
>+ unsigned long time_left;
>+ unsigned int i2c_cmd;
>+ unsigned int addr;
>+ int ret, idx;
>+
>+ ret = owl_i2c_hw_init(i2c_dev);
>+ if (ret)
>+ return ret;
>+
>+ ret = owl_i2c_check_bus_busy(adap);
>+ if (ret)
>+ return ret;
>+
>+ reinit_completion(&i2c_dev->msg_complete);
>+
>+ /* Enable I2C controller interrupt */
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
>+ OWL_I2C_CTL_IRQE, true);
>+
>+ /*
>+ * Select: FIFO enable, Master mode, Stop enable, Data count enable,
>+ * Send start bit
>+ */
>+ i2c_cmd = (OWL_I2C_CMD_SECL | OWL_I2C_CMD_MSS | OWL_I2C_CMD_SE
>+ | OWL_I2C_CMD_NS | OWL_I2C_CMD_DE | OWL_I2C_CMD_SBE);
>+
>+ /* Handle repeated start condition */
>+ if (num > 1) {
>+ /* Set internal address length and enable repeated start */
>+ i2c_cmd |= (OWL_I2C_CMD_AS(msgs[0].len + 1)
>+ | OWL_I2C_CMD_SAS(1) | OWL_I2C_CMD_RBE);
>+
>+ /* Write slave address */
>+ addr = i2c_8bit_addr_from_msg(&msgs[0]);
>+ writel(addr, i2c_dev->base + OWL_I2C_REG_TXDAT);
>+
>+ /* Write internal register address */
>+ for (idx = 0; idx < msgs[0].len; idx++)
>+ writel(msgs[0].buf[idx], i2c_dev->base +
>+ OWL_I2C_REG_TXDAT);
>+
>+ msg = &msgs[1];
>+ } else {
>+ /* Set address length */
>+ i2c_cmd |= OWL_I2C_CMD_AS(1);
>+ msg = &msgs[0];
>+ }
>+
>+ i2c_dev->msg = msg;
>+ i2c_dev->msg_ptr = 0;
>+
>+ /* Set data count for the message */
>+ writel(msg->len, i2c_dev->base + OWL_I2C_REG_DATCNT);
>+
>+ addr = i2c_8bit_addr_from_msg(msg);
>+ writel(addr, i2c_dev->base + OWL_I2C_REG_TXDAT);
>+
>+ if (!(msg->flags & I2C_M_RD)) {
>+ /* Write data to FIFO */
>+ for (idx = 0; idx < msg->len; idx++) {
>+ /* Check for FIFO full */
>+ if (readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT)
>+ & OWL_I2C_FIFOSTAT_TFF)
>+ break;
>+
>+ writel(msg->buf[idx],
>+ i2c_dev->base + OWL_I2C_REG_TXDAT);
>+ }
>+
>+ i2c_dev->msg_ptr = idx;
>+ }
>+
>+ /* Ignore the NACK if needed */
>+ if (msg->flags & I2C_M_IGNORE_NAK)
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
>+ OWL_I2C_FIFOCTL_NIB, true);
>+ else
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
>+ OWL_I2C_FIFOCTL_NIB, false);
>+
>+ /* Start the transfer */
>+ writel(i2c_cmd, i2c_dev->base + OWL_I2C_REG_CMD);
>+
>+ time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
>+ adap->timeout);
>+ if (time_left == 0) {
>+ dev_err(&adap->dev, "Transaction timed out");
>+ /* Send stop condition and release the bus */
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
>+ OWL_I2C_CTL_GBCC_STOP | OWL_I2C_CTL_RB, true);
>+ ret = -ETIMEDOUT;
>+ }
>+
>+ /*
>+ * By default, 0 will be returned if interrupt occurred but no
>+ * read or write happened. Else if msg_ptr equals to message length,
>+ * message count will be returned.
>+ */
Zero is never a valid return value for this function. It has to be either num or a negative error. So, this comment is bad, which makes me assume the code is too. I didn't bother to check any further...
Cheers,
Peter
>+ if (i2c_dev->msg_ptr == msg->len)
>+ ret = num;
>+
>+ /* Disable I2C controller */
>+ owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
>+ OWL_I2C_CTL_EN, false);
>+
>+ return ret;
>+}
>+
>+static const struct i2c_algorithm owl_i2c_algorithm = {
>+ .master_xfer = owl_i2c_master_xfer,
>+ .functionality = owl_i2c_func,
>+};
>+
>+static const struct i2c_adapter_quirks owl_i2c_quirks = {
>+ .flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST,
>+ .max_read_len = 240,
>+ .max_write_len = 240,
>+ .max_comb_1st_msg_len = 6,
>+ .max_comb_2nd_msg_len = 240,
>+};
>+
>+static int owl_i2c_probe(struct platform_device *pdev)
>+{
>+ struct device *dev = &pdev->dev;
>+ struct owl_i2c_dev *i2c_dev;
>+ struct resource *res;
>+ int ret, irq;
>+
>+ i2c_dev = devm_kzalloc(dev, sizeof(*i2c_dev), GFP_KERNEL);
>+ if (!i2c_dev)
>+ return -ENOMEM;
>+
>+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>+ i2c_dev->base = devm_ioremap_resource(dev, res);
>+ if (IS_ERR(i2c_dev->base))
>+ return PTR_ERR(i2c_dev->base);
>+
>+ irq = platform_get_irq(pdev, 0);
>+ if (irq < 0) {
>+ dev_err(dev, "failed to get IRQ number\n");
>+ return irq;
>+ }
>+
>+ if (of_property_read_u32(dev->of_node, "clock-frequency",
>+ &i2c_dev->bus_freq))
>+ i2c_dev->bus_freq = OWL_I2C_DEF_SPEED_HZ;
>+
>+ /* We support only frequencies of 100k and 400k for now */
>+ if (i2c_dev->bus_freq != OWL_I2C_DEF_SPEED_HZ &&
>+ i2c_dev->bus_freq > OWL_I2C_MAX_SPEED_HZ) {
>+ dev_err(dev, "invalid clock-frequency %d\n", i2c_dev->bus_freq);
>+ return -EINVAL;
>+ }
>+
>+ i2c_dev->clk = devm_clk_get(dev, NULL);
>+ if (IS_ERR(i2c_dev->clk)) {
>+ dev_err(dev, "failed to get clock\n");
>+ return PTR_ERR(i2c_dev->clk);
>+ }
>+
>+ ret = clk_prepare_enable(i2c_dev->clk);
>+ if (ret)
>+ return ret;
>+
>+ i2c_dev->clk_rate = clk_get_rate(i2c_dev->clk);
>+ if (!i2c_dev->clk_rate) {
>+ dev_err(dev, "input clock rate should not be zero\n");
>+ ret = -EINVAL;
>+ goto disable_clk;
>+ }
>+
>+ init_completion(&i2c_dev->msg_complete);
>+ i2c_dev->adap.owner = THIS_MODULE;
>+ i2c_dev->adap.algo = &owl_i2c_algorithm;
>+ i2c_dev->adap.timeout = OWL_I2C_TIMEOUT;
>+ i2c_dev->adap.quirks = &owl_i2c_quirks;
>+ i2c_dev->adap.dev.parent = dev;
>+ i2c_dev->adap.dev.of_node = dev->of_node;
>+ snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
>+ "%s", "OWL I2C adapter");
>+ i2c_set_adapdata(&i2c_dev->adap, i2c_dev);
>+
>+ platform_set_drvdata(pdev, i2c_dev);
>+
>+ ret = devm_request_irq(dev, irq, owl_i2c_interrupt, 0, pdev->name,
>+ i2c_dev);
>+ if (ret) {
>+ dev_err(dev, "failed to request irq %d\n", irq);
>+ goto disable_clk;
>+ }
>+
>+ return i2c_add_adapter(&i2c_dev->adap);
>+
>+disable_clk:
>+ clk_disable_unprepare(i2c_dev->clk);
>+
>+ return ret;
>+}
>+
>+static const struct of_device_id owl_i2c_of_match[] = {
>+ {.compatible = "actions,s900-i2c"},
>+ { /* sentinel */ }
>+};
>+MODULE_DEVICE_TABLE(of, owl_i2c_of_match);
>+
>+static struct platform_driver owl_i2c_driver = {
>+ .probe = owl_i2c_probe,
>+ .driver = {
>+ .name = "owl-i2c",
>+ .of_match_table = of_match_ptr(owl_i2c_of_match),
>+ },
>+};
>+module_platform_driver(owl_i2c_driver);
>+
>+MODULE_AUTHOR("David Liu <liuwei@xxxxxxxxxxxxxxxx>");
>+MODULE_AUTHOR("Manivannan Sadhasivam
><manivannan.sadhasivam@xxxxxxxxxx>");
>+MODULE_DESCRIPTION("Actions Semiconductor Owl SoC's I2C driver");
>+MODULE_LICENSE("GPL");