3 files changed, 359 insertions, 0 deletions

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 759ee30dc63a..9f7d5859cf65 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -774,6 +774,19 @@ config I2C_STU300
           This driver can also be built as a module. If so, the module
           will be called i2c-stu300.
 
+config I2C_SUN6I_P2WI
+        tristate "Allwinner sun6i internal P2WI controller"
+        depends on RESET_CONTROLLER
+        depends on MACH_SUN6I || COMPILE_TEST
+        help
+          If you say yes to this option, support will be included for the
+          P2WI (Push/Pull 2 Wire Interface) controller embedded in some sunxi
+          SOCs.
+          The P2WI looks like an SMBus controller (which supports only byte
+          accesses), except that it only supports one slave device.
+          This interface is used to connect to specific PMIC devices (like the
+          AXP221).
+
 config I2C_TEGRA
         tristate "NVIDIA Tegra internal I2C controller"
         depends on ARCH_TEGRA
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 8ac83374cf7e..dd9a7f8e873f 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -75,6 +75,7 @@ obj-$(CONFIG_I2C_SIMTEC)	+= i2c-simtec.o
 obj-$(CONFIG_I2C_SIRF)          += i2c-sirf.o
 obj-$(CONFIG_I2C_ST)            += i2c-st.o
 obj-$(CONFIG_I2C_STU300)        += i2c-stu300.o
+obj-$(CONFIG_I2C_SUN6I_P2WI)    += i2c-sun6i-p2wi.o
 obj-$(CONFIG_I2C_TEGRA)         += i2c-tegra.o
 obj-$(CONFIG_I2C_VERSATILE)     += i2c-versatile.o
 obj-$(CONFIG_I2C_WMT)           += i2c-wmt.o
diff --git a/drivers/i2c/busses/i2c-sun6i-p2wi.c b/drivers/i2c/busses/i2c-sun6i-p2wi.c
new file mode 100644
index 000000000000..f1d3e6f1a409
--- /dev/null
+++ b/drivers/i2c/busses/i2c-sun6i-p2wi.c
@@ -0,0 +1,345 @@
+/*
+ * P2WI (Push-Pull Two Wire Interface) bus driver.
+ *
+ * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ *
+ * The P2WI controller looks like an SMBus controller which only supports byte
+ * data transfers. But, it differs from standard SMBus protocol on several
+ * aspects:
+ * - it supports only one slave device, and thus drop the address field
+ * - it adds a parity bit every 8bits of data
+ * - only one read access is required to read a byte (instead of a write
+ *   followed by a read access in standard SMBus protocol)
+ * - there's no Ack bit after each byte transfer
+ *
+ * This means this bus cannot be used to interface with standard SMBus
+ * devices (the only known device to support this interface is the AXP221
+ * PMIC).
+ *
+ */
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+
+
+/* P2WI registers */
+#define P2WI_CTRL               0x0
+#define P2WI_CCR                0x4
+#define P2WI_INTE               0x8
+#define P2WI_INTS               0xc
+#define P2WI_DADDR0             0x10
+#define P2WI_DADDR1             0x14
+#define P2WI_DLEN               0x18
+#define P2WI_DATA0              0x1c
+#define P2WI_DATA1              0x20
+#define P2WI_LCR                0x24
+#define P2WI_PMCR               0x28
+
+/* CTRL fields */
+#define P2WI_CTRL_START_TRANS           BIT(7)
+#define P2WI_CTRL_ABORT_TRANS           BIT(6)
+#define P2WI_CTRL_GLOBAL_INT_ENB        BIT(1)
+#define P2WI_CTRL_SOFT_RST              BIT(0)
+
+/* CLK CTRL fields */
+#define P2WI_CCR_SDA_OUT_DELAY(v)       (((v) & 0x7) << 8)
+#define P2WI_CCR_MAX_CLK_DIV            0xff
+#define P2WI_CCR_CLK_DIV(v)             ((v) & P2WI_CCR_MAX_CLK_DIV)
+
+/* STATUS fields */
+#define P2WI_INTS_TRANS_ERR_ID(v)       (((v) >> 8) & 0xff)
+#define P2WI_INTS_LOAD_BSY              BIT(2)
+#define P2WI_INTS_TRANS_ERR             BIT(1)
+#define P2WI_INTS_TRANS_OVER            BIT(0)
+
+/* DATA LENGTH fields*/
+#define P2WI_DLEN_READ                  BIT(4)
+#define P2WI_DLEN_DATA_LENGTH(v)        ((v - 1) & 0x7)
+
+/* LINE CTRL fields*/
+#define P2WI_LCR_SCL_STATE              BIT(5)
+#define P2WI_LCR_SDA_STATE              BIT(4)
+#define P2WI_LCR_SCL_CTL                BIT(3)
+#define P2WI_LCR_SCL_CTL_EN             BIT(2)
+#define P2WI_LCR_SDA_CTL                BIT(1)
+#define P2WI_LCR_SDA_CTL_EN             BIT(0)
+
+/* PMU MODE CTRL fields */
+#define P2WI_PMCR_PMU_INIT_SEND         BIT(31)
+#define P2WI_PMCR_PMU_INIT_DATA(v)      (((v) & 0xff) << 16)
+#define P2WI_PMCR_PMU_MODE_REG(v)       (((v) & 0xff) << 8)
+#define P2WI_PMCR_PMU_DEV_ADDR(v)       ((v) & 0xff)
+
+#define P2WI_MAX_FREQ                   6000000
+
+struct p2wi {
+        struct i2c_adapter adapter;
+        struct completion complete;
+        unsigned int status;
+        void __iomem *regs;
+        struct clk *clk;
+        struct reset_control *rstc;
+        int slave_addr;
+};
+
+static irqreturn_t p2wi_interrupt(int irq, void *dev_id)
+{
+        struct p2wi *p2wi = dev_id;
+        unsigned long status;
+
+        status = readl(p2wi->regs + P2WI_INTS);
+        p2wi->status = status;
+
+        /* Clear interrupts */
+        status &= (P2WI_INTS_LOAD_BSY | P2WI_INTS_TRANS_ERR |
+                   P2WI_INTS_TRANS_OVER);
+        writel(status, p2wi->regs + P2WI_INTS);
+
+        complete(&p2wi->complete);
+
+        return IRQ_HANDLED;
+}
+
+static u32 p2wi_functionality(struct i2c_adapter *adap)
+{
+        return I2C_FUNC_SMBUS_BYTE_DATA;
+}
+
+static int p2wi_smbus_xfer(struct i2c_adapter *adap, u16 addr,
+                           unsigned short flags, char read_write,
+                           u8 command, int size, union i2c_smbus_data *data)
+{
+        struct p2wi *p2wi = i2c_get_adapdata(adap);
+        unsigned long dlen = P2WI_DLEN_DATA_LENGTH(1);
+
+        if (p2wi->slave_addr >= 0 && addr != p2wi->slave_addr) {
+                dev_err(&adap->dev, "invalid P2WI address\n");
+                return -EINVAL;
+        }
+
+        if (!data)
+                return -EINVAL;
+
+        writel(command, p2wi->regs + P2WI_DADDR0);
+
+        if (read_write == I2C_SMBUS_READ)
+                dlen |= P2WI_DLEN_READ;
+        else
+                writel(data->byte, p2wi->regs + P2WI_DATA0);
+
+        writel(dlen, p2wi->regs + P2WI_DLEN);
+
+        if (readl(p2wi->regs + P2WI_CTRL) & P2WI_CTRL_START_TRANS) {
+                dev_err(&adap->dev, "P2WI bus busy\n");
+                return -EBUSY;
+        }
+
+        reinit_completion(&p2wi->complete);
+
+        writel(P2WI_INTS_LOAD_BSY | P2WI_INTS_TRANS_ERR | P2WI_INTS_TRANS_OVER,
+               p2wi->regs + P2WI_INTE);
+
+        writel(P2WI_CTRL_START_TRANS | P2WI_CTRL_GLOBAL_INT_ENB,
+               p2wi->regs + P2WI_CTRL);
+
+        wait_for_completion(&p2wi->complete);
+
+        if (p2wi->status & P2WI_INTS_LOAD_BSY) {
+                dev_err(&adap->dev, "P2WI bus busy\n");
+                return -EBUSY;
+        }
+
+        if (p2wi->status & P2WI_INTS_TRANS_ERR) {
+                dev_err(&adap->dev, "P2WI bus xfer error\n");
+                return -ENXIO;
+        }
+
+        if (read_write == I2C_SMBUS_READ)
+                data->byte = readl(p2wi->regs + P2WI_DATA0);
+
+        return 0;
+}
+
+static const struct i2c_algorithm p2wi_algo = {
+        .smbus_xfer = p2wi_smbus_xfer,
+        .functionality = p2wi_functionality,
+};
+
+static const struct of_device_id p2wi_of_match_table[] = {
+        { .compatible = "allwinner,sun6i-a31-p2wi" },
+        {}
+};
+MODULE_DEVICE_TABLE(of, p2wi_of_match_table);
+
+static int p2wi_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct device_node *np = dev->of_node;
+        struct device_node *childnp;
+        unsigned long parent_clk_freq;
+        u32 clk_freq = 100000;
+        struct resource *r;
+        struct p2wi *p2wi;
+        u32 slave_addr;
+        int clk_div;
+        int irq;
+        int ret;
+
+        of_property_read_u32(np, "clock-frequency", &clk_freq);
+        if (clk_freq > P2WI_MAX_FREQ) {
+                dev_err(dev,
+                        "required clock-frequency (%u Hz) is too high (max = 6MHz)",
+                        clk_freq);
+                return -EINVAL;
+        }
+
+        if (of_get_child_count(np) > 1) {
+                dev_err(dev, "P2WI only supports one slave device\n");
+                return -EINVAL;
+        }
+
+        p2wi = devm_kzalloc(dev, sizeof(struct p2wi), GFP_KERNEL);
+        if (!p2wi)
+                return -ENOMEM;
+
+        p2wi->slave_addr = -1;
+
+        /*
+         * Authorize a p2wi node without any children to be able to use an
+         * i2c-dev from userpace.
+         * In this case the slave_addr is set to -1 and won't be checked when
+         * launching a P2WI transfer.
+         */
+        childnp = of_get_next_available_child(np, NULL);
+        if (childnp) {
+                ret = of_property_read_u32(childnp, "reg", &slave_addr);
+                if (ret) {
+                        dev_err(dev, "invalid slave address on node %s\n",
+                                childnp->full_name);
+                        return -EINVAL;
+                }
+
+                p2wi->slave_addr = slave_addr;
+        }
+
+        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        p2wi->regs = devm_ioremap_resource(dev, r);
+        if (IS_ERR(p2wi->regs))
+                return PTR_ERR(p2wi->regs);
+
+        snprintf(p2wi->adapter.name, sizeof(p2wi->adapter.name), pdev->name);
+        irq = platform_get_irq(pdev, 0);
+        if (irq < 0) {
+                dev_err(dev, "failed to retrieve irq: %d\n", ret);
+                return irq;
+        }
+
+        p2wi->clk = devm_clk_get(dev, NULL);
+        if (IS_ERR(p2wi->clk)) {
+                ret = PTR_ERR(p2wi->clk);
+                dev_err(dev, "failed to retrieve clk: %d\n", ret);
+                return ret;
+        }
+
+        ret = clk_prepare_enable(p2wi->clk);
+        if (ret) {
+                dev_err(dev, "failed to enable clk: %d\n", ret);
+                return ret;
+        }
+
+        parent_clk_freq = clk_get_rate(p2wi->clk);
+
+        p2wi->rstc = devm_reset_control_get(dev, NULL);
+        if (IS_ERR(p2wi->rstc)) {
+                ret = PTR_ERR(p2wi->rstc);
+                dev_err(dev, "failed to retrieve reset controller: %d\n", ret);
+                goto err_clk_disable;
+        }
+
+        ret = reset_control_deassert(p2wi->rstc);
+        if (ret) {
+                dev_err(dev, "failed to deassert reset line: %d\n", ret);
+                goto err_clk_disable;
+        }
+
+        init_completion(&p2wi->complete);
+        p2wi->adapter.dev.parent = dev;
+        p2wi->adapter.algo = &p2wi_algo;
+        p2wi->adapter.owner = THIS_MODULE;
+        p2wi->adapter.dev.of_node = pdev->dev.of_node;
+        platform_set_drvdata(pdev, p2wi);
+        i2c_set_adapdata(&p2wi->adapter, p2wi);
+
+        ret = devm_request_irq(dev, irq, p2wi_interrupt, 0, pdev->name, p2wi);
+        if (ret) {
+                dev_err(dev, "can't register interrupt handler irq%d: %d\n",
+                        irq, ret);
+                goto err_reset_assert;
+        }
+
+        writel(P2WI_CTRL_SOFT_RST, p2wi->regs + P2WI_CTRL);
+
+        clk_div = parent_clk_freq / clk_freq;
+        if (!clk_div) {
+                dev_warn(dev,
+                         "clock-frequency is too high, setting it to %lu Hz\n",
+                         parent_clk_freq);
+                clk_div = 1;
+        } else if (clk_div > P2WI_CCR_MAX_CLK_DIV) {
+                dev_warn(dev,
+                         "clock-frequency is too low, setting it to %lu Hz\n",
+                         parent_clk_freq / P2WI_CCR_MAX_CLK_DIV);
+                clk_div = P2WI_CCR_MAX_CLK_DIV;
+        }
+
+        writel(P2WI_CCR_SDA_OUT_DELAY(1) | P2WI_CCR_CLK_DIV(clk_div),
+               p2wi->regs + P2WI_CCR);
+
+        ret = i2c_add_adapter(&p2wi->adapter);
+        if (!ret)
+                return 0;
+
+err_reset_assert:
+        reset_control_assert(p2wi->rstc);
+
+err_clk_disable:
+        clk_disable_unprepare(p2wi->clk);
+
+        return ret;
+}
+
+static int p2wi_remove(struct platform_device *dev)
+{
+        struct p2wi *p2wi = platform_get_drvdata(dev);
+
+        reset_control_assert(p2wi->rstc);
+        clk_disable_unprepare(p2wi->clk);
+        i2c_del_adapter(&p2wi->adapter);
+
+        return 0;
+}
+
+static struct platform_driver p2wi_driver = {
+        .probe  = p2wi_probe,
+        .remove = p2wi_remove,
+        .driver = {
+                .owner = THIS_MODULE,
+                .name = "i2c-sunxi-p2wi",
+                .of_match_table = p2wi_of_match_table,
+        },
+};
+module_platform_driver(p2wi_driver);
+
+MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>");
+MODULE_DESCRIPTION("Allwinner P2WI driver");
+MODULE_LICENSE("GPL v2");