--- /dev/null
+/*
+ * 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");
projects / karo-tx-linux.git / commitdiff