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