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Release 4.11 drivers/i2c/busses/i2c-axxia.c

/*
 * This driver implements I2C master functionality using the LSI API2C
 * controller.
 *
 * NOTE: The controller has a limitation in that it can only do transfers of
 * maximum 255 bytes at a time. If a larger transfer is attempted, error code
 * (-EINVAL) is returned.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 */
#include <linux/clk.h>
#include <linux/clkdev.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>


#define SCL_WAIT_TIMEOUT_NS 25000000

#define I2C_XFER_TIMEOUT    (msecs_to_jiffies(250))

#define I2C_STOP_TIMEOUT    (msecs_to_jiffies(100))

#define FIFO_SIZE           8


#define GLOBAL_CONTROL		0x00

#define   GLOBAL_MST_EN         BIT(0)

#define   GLOBAL_SLV_EN         BIT(1)

#define   GLOBAL_IBML_EN        BIT(2)

#define INTERRUPT_STATUS	0x04

#define INTERRUPT_ENABLE	0x08

#define   INT_SLV               BIT(1)

#define   INT_MST               BIT(0)

#define WAIT_TIMER_CONTROL	0x0c

#define   WT_EN			BIT(15)

#define   WT_VALUE(_x)		((_x) & 0x7fff)

#define IBML_TIMEOUT		0x10

#define IBML_LOW_MEXT		0x14

#define IBML_LOW_SEXT		0x18

#define TIMER_CLOCK_DIV		0x1c

#define I2C_BUS_MONITOR		0x20

#define   BM_SDAC		BIT(3)

#define   BM_SCLC		BIT(2)

#define   BM_SDAS		BIT(1)

#define   BM_SCLS		BIT(0)

#define SOFT_RESET		0x24

#define MST_COMMAND		0x28

#define   CMD_BUSY		(1<<3)

#define   CMD_MANUAL		(0x00 | CMD_BUSY)

#define   CMD_AUTO		(0x01 | CMD_BUSY)

#define MST_RX_XFER		0x2c

#define MST_TX_XFER		0x30

#define MST_ADDR_1		0x34

#define MST_ADDR_2		0x38

#define MST_DATA		0x3c

#define MST_TX_FIFO		0x40

#define MST_RX_FIFO		0x44

#define MST_INT_ENABLE		0x48

#define MST_INT_STATUS		0x4c

#define   MST_STATUS_RFL	(1 << 13) 
/* RX FIFO serivce */

#define   MST_STATUS_TFL	(1 << 12) 
/* TX FIFO service */

#define   MST_STATUS_SNS	(1 << 11) 
/* Manual mode done */

#define   MST_STATUS_SS		(1 << 10) 
/* Automatic mode done */

#define   MST_STATUS_SCC	(1 << 9)  
/* Stop complete */

#define   MST_STATUS_IP		(1 << 8)  
/* Invalid parameter */

#define   MST_STATUS_TSS	(1 << 7)  
/* Timeout */

#define   MST_STATUS_AL		(1 << 6)  
/* Arbitration lost */

#define   MST_STATUS_ND		(1 << 5)  
/* NAK on data phase */

#define   MST_STATUS_NA		(1 << 4)  
/* NAK on address phase */

#define   MST_STATUS_NAK	(MST_STATUS_NA | \
                                 MST_STATUS_ND)

#define   MST_STATUS_ERR	(MST_STATUS_NAK | \
                                 MST_STATUS_AL  | \
                                 MST_STATUS_IP  | \
                                 MST_STATUS_TSS)

#define MST_TX_BYTES_XFRD	0x50

#define MST_RX_BYTES_XFRD	0x54

#define SCL_HIGH_PERIOD		0x80

#define SCL_LOW_PERIOD		0x84

#define SPIKE_FLTR_LEN		0x88

#define SDA_SETUP_TIME		0x8c

#define SDA_HOLD_TIME		0x90

/**
 * axxia_i2c_dev - I2C device context
 * @base: pointer to register struct
 * @msg: pointer to current message
 * @msg_xfrd: number of bytes transferred in msg
 * @msg_err: error code for completed message
 * @msg_complete: xfer completion object
 * @dev: device reference
 * @adapter: core i2c abstraction
 * @i2c_clk: clock reference for i2c input clock
 * @bus_clk_rate: current i2c bus clock rate
 */

struct axxia_i2c_dev {
	
void __iomem *base;
	
struct i2c_msg *msg;
	
size_t msg_xfrd;
	
int msg_err;
	
struct completion msg_complete;
	
struct device *dev;
	
struct i2c_adapter adapter;
	
struct clk *i2c_clk;
	
u32 bus_clk_rate;
};


static void i2c_int_disable(struct axxia_i2c_dev *idev, u32 mask) { u32 int_en; int_en = readl(idev->base + MST_INT_ENABLE); writel(int_en & ~mask, idev->base + MST_INT_ENABLE); }

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static void i2c_int_enable(struct axxia_i2c_dev *idev, u32 mask) { u32 int_en; int_en = readl(idev->base + MST_INT_ENABLE); writel(int_en | mask, idev->base + MST_INT_ENABLE); }

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/** * ns_to_clk - Convert time (ns) to clock cycles for the given clock frequency. */
static u32 ns_to_clk(u64 ns, u32 clk_mhz) { return div_u64(ns * clk_mhz, 1000); }

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static int axxia_i2c_init(struct axxia_i2c_dev *idev) { u32 divisor = clk_get_rate(idev->i2c_clk) / idev->bus_clk_rate; u32 clk_mhz = clk_get_rate(idev->i2c_clk) / 1000000; u32 t_setup; u32 t_high, t_low; u32 tmo_clk; u32 prescale; unsigned long timeout; dev_dbg(idev->dev, "rate=%uHz per_clk=%uMHz -> ratio=1:%u\n", idev->bus_clk_rate, clk_mhz, divisor); /* Reset controller */ writel(0x01, idev->base + SOFT_RESET); timeout = jiffies + msecs_to_jiffies(100); while (readl(idev->base + SOFT_RESET) & 1) { if (time_after(jiffies, timeout)) { dev_warn(idev->dev, "Soft reset failed\n"); break; } } /* Enable Master Mode */ writel(0x1, idev->base + GLOBAL_CONTROL); if (idev->bus_clk_rate <= 100000) { /* Standard mode SCL 50/50, tSU:DAT = 250 ns */ t_high = divisor * 1 / 2; t_low = divisor * 1 / 2; t_setup = ns_to_clk(250, clk_mhz); } else { /* Fast mode SCL 33/66, tSU:DAT = 100 ns */ t_high = divisor * 1 / 3; t_low = divisor * 2 / 3; t_setup = ns_to_clk(100, clk_mhz); } /* SCL High Time */ writel(t_high, idev->base + SCL_HIGH_PERIOD); /* SCL Low Time */ writel(t_low, idev->base + SCL_LOW_PERIOD); /* SDA Setup Time */ writel(t_setup, idev->base + SDA_SETUP_TIME); /* SDA Hold Time, 300ns */ writel(ns_to_clk(300, clk_mhz), idev->base + SDA_HOLD_TIME); /* Filter <50ns spikes */ writel(ns_to_clk(50, clk_mhz), idev->base + SPIKE_FLTR_LEN); /* Configure Time-Out Registers */ tmo_clk = ns_to_clk(SCL_WAIT_TIMEOUT_NS, clk_mhz); /* Find prescaler value that makes tmo_clk fit in 15-bits counter. */ for (prescale = 0; prescale < 15; ++prescale) { if (tmo_clk <= 0x7fff) break; tmo_clk >>= 1; } if (tmo_clk > 0x7fff) tmo_clk = 0x7fff; /* Prescale divider (log2) */ writel(prescale, idev->base + TIMER_CLOCK_DIV); /* Timeout in divided clocks */ writel(WT_EN | WT_VALUE(tmo_clk), idev->base + WAIT_TIMER_CONTROL); /* Mask all master interrupt bits */ i2c_int_disable(idev, ~0); /* Interrupt enable */ writel(0x01, idev->base + INTERRUPT_ENABLE); return 0; }

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static int i2c_m_rd(const struct i2c_msg *msg) { return (msg->flags & I2C_M_RD) != 0; }

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static int i2c_m_ten(const struct i2c_msg *msg) { return (msg->flags & I2C_M_TEN) != 0; }

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static int i2c_m_recv_len(const struct i2c_msg *msg) { return (msg->flags & I2C_M_RECV_LEN) != 0; }

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/** * axxia_i2c_empty_rx_fifo - Fetch data from RX FIFO and update SMBus block * transfer length if this is the first byte of such a transfer. */
static int axxia_i2c_empty_rx_fifo(struct axxia_i2c_dev *idev) { struct i2c_msg *msg = idev->msg; size_t rx_fifo_avail = readl(idev->base + MST_RX_FIFO); int bytes_to_transfer = min(rx_fifo_avail, msg->len - idev->msg_xfrd); while (bytes_to_transfer-- > 0) { int c = readl(idev->base + MST_DATA); if (idev->msg_xfrd == 0 && i2c_m_recv_len(msg)) { /* * Check length byte for SMBus block read */ if (c <= 0 || c > I2C_SMBUS_BLOCK_MAX) { idev->msg_err = -EPROTO; i2c_int_disable(idev, ~0); complete(&idev->msg_complete); break; } msg->len = 1 + c; writel(msg->len, idev->base + MST_RX_XFER); } msg->buf[idev->msg_xfrd++] = c; } return 0; }

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/** * axxia_i2c_fill_tx_fifo - Fill TX FIFO from current message buffer. * @return: Number of bytes left to transfer. */
static int axxia_i2c_fill_tx_fifo(struct axxia_i2c_dev *idev) { struct i2c_msg *msg = idev->msg; size_t tx_fifo_avail = FIFO_SIZE - readl(idev->base + MST_TX_FIFO); int bytes_to_transfer = min(tx_fifo_avail, msg->len - idev->msg_xfrd); int ret = msg->len - idev->msg_xfrd - bytes_to_transfer; while (bytes_to_transfer-- > 0) writel(msg->buf[idev->msg_xfrd++], idev->base + MST_DATA); return ret; }

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static irqreturn_t axxia_i2c_isr(int irq, void *_dev) { struct axxia_i2c_dev *idev = _dev; u32 status; if (!(readl(idev->base + INTERRUPT_STATUS) & INT_MST)) return IRQ_NONE; /* Read interrupt status bits */ status = readl(idev->base + MST_INT_STATUS); if (!idev->msg) { dev_warn(idev->dev, "unexpected interrupt\n"); goto out; } /* RX FIFO needs service? */ if (i2c_m_rd(idev->msg) && (status & MST_STATUS_RFL)) axxia_i2c_empty_rx_fifo(idev); /* TX FIFO needs service? */ if (!i2c_m_rd(idev->msg) && (status & MST_STATUS_TFL)) { if (axxia_i2c_fill_tx_fifo(idev) == 0) i2c_int_disable(idev, MST_STATUS_TFL); } if (status & MST_STATUS_SCC) { /* Stop completed */ i2c_int_disable(idev, ~0); complete(&idev->msg_complete); } else if (status & MST_STATUS_SNS) { /* Transfer done */ i2c_int_disable(idev, ~0); if (i2c_m_rd(idev->msg) && idev->msg_xfrd < idev->msg->len) axxia_i2c_empty_rx_fifo(idev); complete(&idev->msg_complete); } else if (unlikely(status & MST_STATUS_ERR)) { /* Transfer error */ i2c_int_disable(idev, ~0); if (status & MST_STATUS_AL) idev->msg_err = -EAGAIN; else if (status & MST_STATUS_NAK) idev->msg_err = -ENXIO; else idev->msg_err = -EIO; dev_dbg(idev->dev, "error %#x, addr=%#x rx=%u/%u tx=%u/%u\n", status, idev->msg->addr, readl(idev->base + MST_RX_BYTES_XFRD), readl(idev->base + MST_RX_XFER), readl(idev->base + MST_TX_BYTES_XFRD), readl(idev->base + MST_TX_XFER)); complete(&idev->msg_complete); } out: /* Clear interrupt */ writel(INT_MST, idev->base + INTERRUPT_STATUS); return IRQ_HANDLED; }

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static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg) { u32 int_mask = MST_STATUS_ERR | MST_STATUS_SNS; u32 rx_xfer, tx_xfer; u32 addr_1, addr_2; unsigned long time_left; idev->msg = msg; idev->msg_xfrd = 0; idev->msg_err = 0; reinit_completion(&idev->msg_complete); if (i2c_m_ten(msg)) { /* 10-bit address * addr_1: 5'b11110 | addr[9:8] | (R/nW) * addr_2: addr[7:0] */ addr_1 = 0xF0 | ((msg->addr >> 7) & 0x06); addr_2 = msg->addr & 0xFF; } else { /* 7-bit address * addr_1: addr[6:0] | (R/nW) * addr_2: dont care */ addr_1 = (msg->addr << 1) & 0xFF; addr_2 = 0; } if (i2c_m_rd(msg)) { /* I2C read transfer */ rx_xfer = i2c_m_recv_len(msg) ? I2C_SMBUS_BLOCK_MAX : msg->len; tx_xfer = 0; addr_1 |= 1; /* Set the R/nW bit of the address */ } else { /* I2C write transfer */ rx_xfer = 0; tx_xfer = msg->len; } writel(rx_xfer, idev->base + MST_RX_XFER); writel(tx_xfer, idev->base + MST_TX_XFER); writel(addr_1, idev->base + MST_ADDR_1); writel(addr_2, idev->base + MST_ADDR_2); if (i2c_m_rd(msg)) int_mask |= MST_STATUS_RFL; else if (axxia_i2c_fill_tx_fifo(idev) != 0) int_mask |= MST_STATUS_TFL; /* Start manual mode */ writel(CMD_MANUAL, idev->base + MST_COMMAND); i2c_int_enable(idev, int_mask); time_left = wait_for_completion_timeout(&idev->msg_complete, I2C_XFER_TIMEOUT); i2c_int_disable(idev, int_mask); if (readl(idev->base + MST_COMMAND) & CMD_BUSY) dev_warn(idev->dev, "busy after xfer\n"); if (time_left == 0) idev->msg_err = -ETIMEDOUT; if (idev->msg_err == -ETIMEDOUT) i2c_recover_bus(&idev->adapter); if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO) axxia_i2c_init(idev); return idev->msg_err; }

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static int axxia_i2c_stop(struct axxia_i2c_dev *idev) { u32 int_mask = MST_STATUS_ERR | MST_STATUS_SCC; unsigned long time_left; reinit_completion(&idev->msg_complete); /* Issue stop */ writel(0xb, idev->base + MST_COMMAND); i2c_int_enable(idev, int_mask); time_left = wait_for_completion_timeout(&idev->msg_complete, I2C_STOP_TIMEOUT); i2c_int_disable(idev, int_mask); if (time_left == 0) return -ETIMEDOUT; if (readl(idev->base + MST_COMMAND) & CMD_BUSY) dev_warn(idev->dev, "busy after stop\n"); return 0; }

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static int axxia_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) { struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); int i; int ret = 0; for (i = 0; ret == 0 && i < num; ++i) ret = axxia_i2c_xfer_msg(idev, &msgs[i]); axxia_i2c_stop(idev); return ret ? : i; }

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static int axxia_i2c_get_scl(struct i2c_adapter *adap) { struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); return !!(readl(idev->base + I2C_BUS_MONITOR) & BM_SCLS); }

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static void axxia_i2c_set_scl(struct i2c_adapter *adap, int val) { struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); u32 tmp; /* Preserve SDA Control */ tmp = readl(idev->base + I2C_BUS_MONITOR) & BM_SDAC; if (!val) tmp |= BM_SCLC; writel(tmp, idev->base + I2C_BUS_MONITOR); }

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static int axxia_i2c_get_sda(struct i2c_adapter *adap) { struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); return !!(readl(idev->base + I2C_BUS_MONITOR) & BM_SDAS); }

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static struct i2c_bus_recovery_info axxia_i2c_recovery_info = { .recover_bus = i2c_generic_scl_recovery, .get_scl = axxia_i2c_get_scl, .set_scl = axxia_i2c_set_scl, .get_sda = axxia_i2c_get_sda, };
static u32 axxia_i2c_func(struct i2c_adapter *adap) { u32 caps = (I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA); return caps; }

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static const struct i2c_algorithm axxia_i2c_algo = { .master_xfer = axxia_i2c_xfer, .functionality = axxia_i2c_func, }; static const struct i2c_adapter_quirks axxia_i2c_quirks = { .max_read_len = 255, .max_write_len = 255, };
static int axxia_i2c_probe(struct platform_device *pdev) { struct device_node *np = pdev->dev.of_node; struct axxia_i2c_dev *idev = NULL; struct resource *res; void __iomem *base; int irq; int ret = 0; idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL); if (!idev) return -ENOMEM; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(base)) return PTR_ERR(base); irq = platform_get_irq(pdev, 0); if (irq < 0) { dev_err(&pdev->dev, "missing interrupt resource\n"); return irq; } idev->i2c_clk = devm_clk_get(&pdev->dev, "i2c"); if (IS_ERR(idev->i2c_clk)) { dev_err(&pdev->dev, "missing clock\n"); return PTR_ERR(idev->i2c_clk); } idev->base = base; idev->dev = &pdev->dev; init_completion(&idev->msg_complete); of_property_read_u32(np, "clock-frequency", &idev->bus_clk_rate); if (idev->bus_clk_rate == 0) idev->bus_clk_rate = 100000; /* default clock rate */ ret = axxia_i2c_init(idev); if (ret) { dev_err(&pdev->dev, "failed to initialize\n"); return ret; } ret = devm_request_irq(&pdev->dev, irq, axxia_i2c_isr, 0, pdev->name, idev); if (ret) { dev_err(&pdev->dev, "failed to claim IRQ%d\n", irq); return ret; } ret = clk_prepare_enable(idev->i2c_clk); if (ret) { dev_err(&pdev->dev, "failed to enable clock\n"); return ret; } i2c_set_adapdata(&idev->adapter, idev); strlcpy(idev->adapter.name, pdev->name, sizeof(idev->adapter.name)); idev->adapter.owner = THIS_MODULE; idev->adapter.algo = &axxia_i2c_algo; idev->adapter.bus_recovery_info = &axxia_i2c_recovery_info; idev->adapter.quirks = &axxia_i2c_quirks; idev->adapter.dev.parent = &pdev->dev; idev->adapter.dev.of_node = pdev->dev.of_node; platform_set_drvdata(pdev, idev); ret = i2c_add_adapter(&idev->adapter); if (ret) { clk_disable_unprepare(idev->i2c_clk); return ret; } return 0; }

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static int axxia_i2c_remove(struct platform_device *pdev) { struct axxia_i2c_dev *idev = platform_get_drvdata(pdev); clk_disable_unprepare(idev->i2c_clk); i2c_del_adapter(&idev->adapter); return 0; }

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/* Match table for of_platform binding */ static const struct of_device_id axxia_i2c_of_match[] = { { .compatible = "lsi,api2c", }, {}, }; MODULE_DEVICE_TABLE(of, axxia_i2c_of_match); static struct platform_driver axxia_i2c_driver = { .probe = axxia_i2c_probe, .remove = axxia_i2c_remove, .driver = { .name = "axxia-i2c", .of_match_table = axxia_i2c_of_match, }, }; module_platform_driver(axxia_i2c_driver); MODULE_DESCRIPTION("Axxia I2C Bus driver"); MODULE_AUTHOR("Anders Berg <anders.berg@lsi.com>"); MODULE_LICENSE("GPL v2");

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