[PATCH v3] i2c: vt8500: Add support for I2C bus on Wondermedia SoCs
Tony Prisk
linux at prisktech.co.nz
Fri Jun 14 17:52:16 EDT 2013
This patch adds support for the I2C bus controllers found on Wondermedia
8xxx-series SoCs. Only master-mode is supported.
Signed-off-by: Tony Prisk <linux at prisktech.co.nz>
---
v3 changes:
Included the v2 changes for clarity.
Tidy up the I2C_NO_START code properly.
Remove the alias handling and allow the core to do it.
Change MODULE_LICENSE to "GPL" as per module.h comments.
v2 changes:
Rewrite wmt_i2c_wait_bus_not_busy() as per Wolfram/Russell.
Fix init_completion and INIT_COMPLETION usages.
Remove magic value in wmt_i2c_reset_hardware().
Remove test for (!np) in wmt_i2c_probe() as we only support devicetree anyway.
Remove reference to ->class = I2C_CLASS_HWMON.
.../devicetree/bindings/i2c/i2c-vt8500.txt | 24 +
MAINTAINERS | 1 +
drivers/i2c/busses/Kconfig | 10 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-wmt.c | 479 ++++++++++++++++++++
5 files changed, 515 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-vt8500.txt
create mode 100644 drivers/i2c/busses/i2c-wmt.c
diff --git a/Documentation/devicetree/bindings/i2c/i2c-vt8500.txt b/Documentation/devicetree/bindings/i2c/i2c-vt8500.txt
new file mode 100644
index 0000000..94a425e
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-vt8500.txt
@@ -0,0 +1,24 @@
+* Wondermedia I2C Controller
+
+Required properties :
+
+ - compatible : should be "wm,wm8505-i2c"
+ - reg : Offset and length of the register set for the device
+ - interrupts : <IRQ> where IRQ is the interrupt number
+ - clocks : phandle to the I2C clock source
+
+Optional properties :
+
+ - clock-frequency : desired I2C bus clock frequency in Hz.
+ Valid values are 100000 and 400000.
+ Default to 100000 if not specified, or invalid value.
+
+Example :
+
+ i2c_0: i2c at d8280000 {
+ compatible = "wm,wm8505-i2c";
+ reg = <0xd8280000 0x1000>;
+ interrupts = <19>;
+ clocks = <&clki2c0>;
+ clock-frequency = <400000>;
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index 3d7782b..44ea994 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1285,6 +1285,7 @@ S: Maintained
F: arch/arm/mach-vt8500/
F: drivers/clocksource/vt8500_timer.c
F: drivers/gpio/gpio-vt8500.c
+F: drivers/i2c/busses/i2c-wmt.c
F: drivers/mmc/host/wmt-sdmmc.c
F: drivers/pwm/pwm-vt8500.c
F: drivers/rtc/rtc-vt8500.c
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 631736e..89e7ec2 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -724,6 +724,16 @@ config I2C_VERSATILE
This driver can also be built as a module. If so, the module
will be called i2c-versatile.
+config I2C_WMT
+ tristate "Wondermedia WM8xxx SoC I2C bus support"
+ depends on ARCH_VT8500
+ help
+ Say yes if you want to support the I2C bus on Wondermedia 8xxx-series
+ SoCs.
+
+ This driver can also be built as a module. If so, the module will be
+ called i2c-wmt.
+
config I2C_OCTEON
tristate "Cavium OCTEON I2C bus support"
depends on CPU_CAVIUM_OCTEON
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 8f4fc23..3ba94a9 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -71,6 +71,7 @@ obj-$(CONFIG_I2C_SIRF) += i2c-sirf.o
obj-$(CONFIG_I2C_STU300) += i2c-stu300.o
obj-$(CONFIG_I2C_TEGRA) += i2c-tegra.o
obj-$(CONFIG_I2C_VERSATILE) += i2c-versatile.o
+obj-$(CONFIG_I2C_WMT) += i2c-wmt.o
obj-$(CONFIG_I2C_OCTEON) += i2c-octeon.o
obj-$(CONFIG_I2C_XILINX) += i2c-xiic.o
obj-$(CONFIG_I2C_XLR) += i2c-xlr.o
diff --git a/drivers/i2c/busses/i2c-wmt.c b/drivers/i2c/busses/i2c-wmt.c
new file mode 100644
index 0000000..19f6f35
--- /dev/null
+++ b/drivers/i2c/busses/i2c-wmt.c
@@ -0,0 +1,479 @@
+/*
+ * Wondermedia I2C Master Mode Driver
+ *
+ * Copyright (C) 2012 Tony Prisk <linux at prisktech.co.nz>
+ *
+ * Derived from GPLv2+ licensed source:
+ * - Copyright (C) 2008 WonderMedia Technologies, 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, or
+ * (at your option) any later version. as published by the Free Software
+ * Foundation
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_i2c.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+
+#define REG_CR 0x00
+#define REG_TCR 0x02
+#define REG_CSR 0x04
+#define REG_ISR 0x06
+#define REG_IMR 0x08
+#define REG_CDR 0x0A
+#define REG_TR 0x0C
+#define REG_MCR 0x0E
+#define REG_SLAVE_CR 0x10
+#define REG_SLAVE_SR 0x12
+#define REG_SLAVE_ISR 0x14
+#define REG_SLAVE_IMR 0x16
+#define REG_SLAVE_DR 0x18
+#define REG_SLAVE_TR 0x1A
+
+/* REG_CR Bit fields */
+#define CR_TX_NEXT_ACK 0x0000
+#define CR_ENABLE 0x0001
+#define CR_TX_NEXT_NO_ACK 0x0002
+#define CR_TX_END 0x0004
+#define CR_CPU_RDY 0x0008
+#define SLAV_MODE_SEL 0x8000
+
+/* REG_TCR Bit fields */
+#define TCR_STANDARD_MODE 0x0000
+#define TCR_MASTER_WRITE 0x0000
+#define TCR_HS_MODE 0x2000
+#define TCR_MASTER_READ 0x4000
+#define TCR_FAST_MODE 0x8000
+#define TCR_SLAVE_ADDR_MASK 0x007F
+
+/* REG_ISR Bit fields */
+#define ISR_NACK_ADDR 0x0001
+#define ISR_BYTE_END 0x0002
+#define ISR_SCL_TIMEOUT 0x0004
+#define ISR_WRITE_ALL 0x0007
+
+/* REG_IMR Bit fields */
+#define IMR_ENABLE_ALL 0x0007
+
+/* REG_CSR Bit fields */
+#define CSR_RCV_NOT_ACK 0x0001
+#define CSR_RCV_ACK_MASK 0x0001
+#define CSR_READY_MASK 0x0002
+
+/* REG_TR */
+#define SCL_TIMEOUT(x) (((x) & 0xFF) << 16)
+#define TR_STD 0x0064
+#define TR_HS 0x0019
+
+/* REG_MCR */
+#define MCR_APB_96M 7
+#define MCR_APB_166M 12
+
+#define I2C_MODE_STANDARD 0
+#define I2C_MODE_FAST 1
+
+#define WMT_I2C_TIMEOUT (msecs_to_jiffies(1000))
+
+struct wmt_i2c_dev {
+ struct i2c_adapter adapter;
+ struct completion complete;
+ struct device *dev;
+ void __iomem *base;
+ struct clk *clk;
+ int mode;
+ int irq;
+ u16 cmd_status;
+};
+
+static int wmt_i2c_wait_bus_not_busy(struct wmt_i2c_dev *i2c_dev)
+{
+ unsigned long timeout;
+
+ timeout = jiffies + WMT_I2C_TIMEOUT;
+ while (!(readw(i2c_dev->base + REG_CSR) & CSR_READY_MASK)) {
+ if (time_after(jiffies, timeout)) {
+ dev_warn(i2c_dev->dev, "timeout waiting for bus ready\n");
+ return -EBUSY;
+ }
+ msleep(20);
+ }
+
+ return 0;
+}
+
+static int wmt_check_status(struct wmt_i2c_dev *i2c_dev)
+{
+ int ret = 0;
+
+ if (i2c_dev->cmd_status & ISR_NACK_ADDR)
+ ret = -EIO;
+
+ if (i2c_dev->cmd_status & ISR_SCL_TIMEOUT)
+ ret = -ETIMEDOUT;
+
+ return ret;
+}
+
+static int wmt_i2c_write(struct i2c_adapter *adap, struct i2c_msg *pmsg,
+ int last)
+{
+ struct wmt_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
+ u16 val, tcr_val;
+ int ret, wait_result;
+ int xfer_len = 0;
+
+ if (!(pmsg->flags & I2C_M_NOSTART)) {
+ ret = wmt_i2c_wait_bus_not_busy(i2c_dev);
+ if (ret < 0)
+ return ret;
+ }
+
+ if (pmsg->len == 0) {
+ /*
+ * We still need to run through the while (..) once, so
+ * start at -1 and break out early from the loop
+ */
+ xfer_len = -1;
+ writew(0, i2c_dev->base + REG_CDR);
+ } else {
+ writew(pmsg->buf[0] & 0xFF, i2c_dev->base + REG_CDR);
+ }
+
+ if (!(pmsg->flags & I2C_M_NOSTART)) {
+ val = readw(i2c_dev->base + REG_CR);
+ val &= ~CR_TX_END;
+ writew(val, i2c_dev->base + REG_CR);
+
+ val = readw(i2c_dev->base + REG_CR);
+ val |= CR_CPU_RDY;
+ writew(val, i2c_dev->base + REG_CR);
+ }
+
+ INIT_COMPLETION(i2c_dev->complete);
+
+ if (i2c_dev->mode == I2C_MODE_STANDARD)
+ tcr_val = TCR_STANDARD_MODE;
+ else
+ tcr_val = TCR_FAST_MODE;
+
+ tcr_val |= (TCR_MASTER_WRITE | (pmsg->addr & TCR_SLAVE_ADDR_MASK));
+
+ writew(tcr_val, i2c_dev->base + REG_TCR);
+
+ if (pmsg->flags & I2C_M_NOSTART) {
+ val = readw(i2c_dev->base + REG_CR);
+ val |= CR_CPU_RDY;
+ writew(val, i2c_dev->base + REG_CR);
+ }
+
+ while (xfer_len < pmsg->len) {
+ wait_result = wait_for_completion_timeout(&i2c_dev->complete,
+ 500 * HZ / 1000);
+
+ if (wait_result == 0)
+ return -ETIMEDOUT;
+
+ ret = wmt_check_status(i2c_dev);
+ if (ret)
+ return ret;
+
+ xfer_len++;
+
+ val = readw(i2c_dev->base + REG_CSR);
+ if ((val & CSR_RCV_ACK_MASK) == CSR_RCV_NOT_ACK) {
+ dev_dbg(i2c_dev->dev, "write RCV NACK error\n");
+ return -EIO;
+ }
+
+ if (pmsg->len == 0) {
+ val = CR_TX_END | CR_CPU_RDY | CR_ENABLE;
+ writew(val, i2c_dev->base + REG_CR);
+ break;
+ }
+
+ if (xfer_len == pmsg->len) {
+ if (last != 1)
+ writew(CR_ENABLE, i2c_dev->base + REG_CR);
+ } else {
+ writew(pmsg->buf[xfer_len] & 0xFF, i2c_dev->base +
+ REG_CDR);
+ writew(CR_CPU_RDY | CR_ENABLE, i2c_dev->base + REG_CR);
+ }
+ }
+
+ return 0;
+}
+
+static int wmt_i2c_read(struct i2c_adapter *adap, struct i2c_msg *pmsg,
+ int last)
+{
+ struct wmt_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
+ u16 val, tcr_val;
+ int ret, wait_result;
+ u32 xfer_len = 0;
+
+ if (!(pmsg->flags & I2C_M_NOSTART)) {
+ ret = wmt_i2c_wait_bus_not_busy(i2c_dev);
+ if (ret < 0)
+ return ret;
+ }
+
+ val = readw(i2c_dev->base + REG_CR);
+ val &= ~CR_TX_END;
+ writew(val, i2c_dev->base + REG_CR);
+
+ val = readw(i2c_dev->base + REG_CR);
+ val &= ~CR_TX_NEXT_NO_ACK;
+ writew(val, i2c_dev->base + REG_CR);
+
+ if (!(pmsg->flags & I2C_M_NOSTART)) {
+ val = readw(i2c_dev->base + REG_CR);
+ val |= CR_CPU_RDY;
+ writew(val, i2c_dev->base + REG_CR);
+ }
+
+ if (pmsg->len == 1) {
+ val = readw(i2c_dev->base + REG_CR);
+ val |= CR_TX_NEXT_NO_ACK;
+ writew(val, i2c_dev->base + REG_CR);
+ }
+
+ INIT_COMPLETION(i2c_dev->complete);
+
+ if (i2c_dev->mode == I2C_MODE_STANDARD)
+ tcr_val = TCR_STANDARD_MODE;
+ else
+ tcr_val = TCR_FAST_MODE;
+
+ tcr_val |= TCR_MASTER_READ | (pmsg->addr & TCR_SLAVE_ADDR_MASK);
+
+ writew(tcr_val, i2c_dev->base + REG_TCR);
+
+ if (pmsg->flags & I2C_M_NOSTART) {
+ val = readw(i2c_dev->base + REG_CR);
+ val |= CR_CPU_RDY;
+ writew(val, i2c_dev->base + REG_CR);
+ }
+
+ while (xfer_len < pmsg->len) {
+ wait_result = wait_for_completion_timeout(&i2c_dev->complete,
+ 500 * HZ / 1000);
+
+ if (!wait_result)
+ return -ETIMEDOUT;
+
+ ret = wmt_check_status(i2c_dev);
+ if (ret)
+ return ret;
+
+ pmsg->buf[xfer_len] = readw(i2c_dev->base + REG_CDR) >> 8;
+ xfer_len++;
+
+ if (xfer_len == pmsg->len - 1) {
+ val = readw(i2c_dev->base + REG_CR);
+ val |= (CR_TX_NEXT_NO_ACK | CR_CPU_RDY);
+ writew(val, i2c_dev->base + REG_CR);
+ } else {
+ val = readw(i2c_dev->base + REG_CR);
+ val |= CR_CPU_RDY;
+ writew(val, i2c_dev->base + REG_CR);
+ }
+ }
+
+ return 0;
+}
+
+static int wmt_i2c_xfer(struct i2c_adapter *adap,
+ struct i2c_msg msgs[],
+ int num)
+{
+ struct i2c_msg *pmsg;
+ int i, is_last;
+ int ret = 0;
+
+ for (i = 0; ret >= 0 && i < num; i++) {
+ is_last = ((i + 1) == num);
+
+ pmsg = &msgs[i];
+ if (pmsg->flags & I2C_M_RD)
+ ret = wmt_i2c_read(adap, pmsg, is_last);
+ else
+ ret = wmt_i2c_write(adap, pmsg, is_last);
+ }
+
+ return (ret < 0) ? ret : i;
+}
+
+static u32 wmt_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
+}
+
+static const struct i2c_algorithm wmt_i2c_algo = {
+ .master_xfer = wmt_i2c_xfer,
+ .functionality = wmt_i2c_func,
+};
+
+static irqreturn_t wmt_i2c_isr(int irq, void *data)
+{
+ struct wmt_i2c_dev *i2c_dev = data;
+
+ /* save the status and write-clear it */
+ i2c_dev->cmd_status = readw(i2c_dev->base + REG_ISR);
+ writew(i2c_dev->cmd_status, i2c_dev->base + REG_ISR);
+
+ complete(&i2c_dev->complete);
+
+ return IRQ_HANDLED;
+}
+
+static int wmt_i2c_reset_hardware(struct wmt_i2c_dev *i2c_dev)
+{
+ int err;
+
+ err = clk_prepare_enable(i2c_dev->clk);
+ if (err) {
+ dev_err(i2c_dev->dev, "failed to enable clock\n");
+ return err;
+ }
+
+ err = clk_set_rate(i2c_dev->clk, 20000000);
+ if (err) {
+ dev_err(i2c_dev->dev, "failed to set clock = 20Mhz\n");
+ return err;
+ }
+
+ writew(0, i2c_dev->base + REG_CR);
+ writew(MCR_APB_166M, i2c_dev->base + REG_MCR);
+ writew(ISR_WRITE_ALL, i2c_dev->base + REG_ISR);
+ writew(IMR_ENABLE_ALL, i2c_dev->base + REG_IMR);
+ writew(CR_ENABLE, i2c_dev->base + REG_CR);
+ readw(i2c_dev->base + REG_CSR); /* read clear */
+ writew(ISR_WRITE_ALL, i2c_dev->base + REG_ISR);
+
+ if (i2c_dev->mode == I2C_MODE_STANDARD)
+ writew(SCL_TIMEOUT(128) | TR_STD, i2c_dev->base + REG_TR);
+ else
+ writew(SCL_TIMEOUT(128) | TR_HS, i2c_dev->base + REG_TR);
+
+ return 0;
+}
+
+static int wmt_i2c_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct wmt_i2c_dev *i2c_dev;
+ struct i2c_adapter *adap;
+ struct resource *res;
+ int err;
+ u32 clk_rate;
+
+ i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
+ if (!i2c_dev) {
+ dev_err(&pdev->dev, "device memory allocation failed\n");
+ return -ENOMEM;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ i2c_dev->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(i2c_dev->base))
+ return PTR_ERR(i2c_dev->base);
+
+ i2c_dev->irq = irq_of_parse_and_map(np, 0);
+ if (!i2c_dev->irq) {
+ dev_err(&pdev->dev, "irq missing or invalid\n");
+ return -EINVAL;
+ }
+
+ i2c_dev->clk = of_clk_get(np, 0);
+ if (IS_ERR(i2c_dev->clk)) {
+ dev_err(&pdev->dev, "unable to request clock\n");
+ return PTR_ERR(i2c_dev->clk);
+ }
+
+ i2c_dev->mode = I2C_MODE_STANDARD;
+ err = of_property_read_u32(np, "clock-frequency", &clk_rate);
+ if ((!err) && (clk_rate == 400000))
+ i2c_dev->mode = I2C_MODE_FAST;
+
+ i2c_dev->dev = &pdev->dev;
+
+ err = devm_request_irq(&pdev->dev, i2c_dev->irq, wmt_i2c_isr, 0,
+ "i2c", i2c_dev);
+ if (err) {
+ dev_err(&pdev->dev, "failed to request irq %i\n", i2c_dev->irq);
+ return err;
+ }
+
+ adap = &i2c_dev->adapter;
+ i2c_set_adapdata(adap, i2c_dev);
+ strlcpy(adap->name, "WMT I2C adapter", sizeof(adap->name));
+ adap->owner = THIS_MODULE;
+ adap->algo = &wmt_i2c_algo;
+ adap->dev.parent = &pdev->dev;
+ adap->dev.of_node = pdev->dev.of_node;
+
+ init_completion(&i2c_dev->complete);
+
+ err = wmt_i2c_reset_hardware(i2c_dev);
+ if (err) {
+ dev_err(&pdev->dev, "error initializing hardware\n");
+ return err;
+ }
+
+ err = i2c_add_adapter(adap);
+ if (err) {
+ dev_err(&pdev->dev, "failed to add adapter\n");
+ return err;
+ }
+
+ platform_set_drvdata(pdev, i2c_dev);
+
+ of_i2c_register_devices(adap);
+
+ return 0;
+}
+
+static int wmt_i2c_remove(struct platform_device *pdev)
+{
+ struct wmt_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+
+ /* Disable interrupts, clock and delete adapter */
+ writew(0, i2c_dev->base + REG_IMR);
+ clk_disable_unprepare(i2c_dev->clk);
+ i2c_del_adapter(&i2c_dev->adapter);
+
+ return 0;
+}
+
+static struct of_device_id wmt_i2c_dt_ids[] = {
+ { .compatible = "wm,wm8505-i2c" },
+ { /* Sentinel */ },
+};
+
+static struct platform_driver wmt_i2c_driver = {
+ .probe = wmt_i2c_probe,
+ .remove = wmt_i2c_remove,
+ .driver = {
+ .name = "wmt-i2c",
+ .owner = THIS_MODULE,
+ .of_match_table = wmt_i2c_dt_ids,
+ },
+};
+
+module_platform_driver(wmt_i2c_driver);
+
+MODULE_DESCRIPTION("Wondermedia I2C master-mode bus adapter");
+MODULE_AUTHOR("Tony Prisk <linux at prisktech.co.nz>");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, wmt_i2c_dt_ids);
--
1.7.9.5
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