| /* |
| * 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/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 = I2C_MAX_STANDARD_MODE_FREQ; |
| 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 %pOF\n", |
| childnp); |
| return -EINVAL; |
| } |
| |
| p2wi->slave_addr = slave_addr; |
| } |
| |
| p2wi->regs = devm_platform_ioremap_resource(pdev, 0); |
| if (IS_ERR(p2wi->regs)) |
| return PTR_ERR(p2wi->regs); |
| |
| strlcpy(p2wi->adapter.name, pdev->name, sizeof(p2wi->adapter.name)); |
| irq = platform_get_irq(pdev, 0); |
| if (irq < 0) |
| 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_exclusive(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 = { |
| .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"); |