diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-sun6i-p2wi.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-sun6i-p2wi.c | 344 |
1 files changed, 344 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-sun6i-p2wi.c b/drivers/i2c/busses/i2c-sun6i-p2wi.c new file mode 100644 index 000000000..f2ed13b55 --- /dev/null +++ b/drivers/i2c/busses/i2c-sun6i-p2wi.c @@ -0,0 +1,344 @@ +/* + * 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 (clk_freq == 0) { + dev_err(dev, "clock-frequency is set to 0 in DT\n"); + 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); + + strscpy(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"); |