From 64d3336b3a83c44f9cab909c07a22d805aade63b Mon Sep 17 00:00:00 2001 From: Ed Nash Date: Wed, 6 Feb 2013 15:48:38 -0500 Subject: add semaphore protection with MQX of I2C bus --- arch/arm/mach-mvf/Makefile | 2 +- arch/arm/mach-mvf/mvf_sema4.c | 234 ++++++++++++++++++++++++++++++++++++++++++ drivers/i2c/busses/i2c-imx.c | 22 ++++ include/linux/mvf_sema4.h | 15 +++ 4 files changed, 272 insertions(+), 1 deletion(-) create mode 100644 arch/arm/mach-mvf/mvf_sema4.c create mode 100644 include/linux/mvf_sema4.h diff --git a/arch/arm/mach-mvf/Makefile b/arch/arm/mach-mvf/Makefile index e25fb28b7216..fdbd22479609 100644 --- a/arch/arm/mach-mvf/Makefile +++ b/arch/arm/mach-mvf/Makefile @@ -3,7 +3,7 @@ # # Object file lists. -obj-y := cpu.o mm.o system.o devices.o dummy_gpio.o irq.o bus_freq.o mvf_fec.o usb_dr.o usb_dr2.o pm.o +obj-y := cpu.o mm.o system.o devices.o dummy_gpio.o irq.o bus_freq.o mvf_fec.o usb_dr.o usb_dr2.o pm.o mvf_sema4.o obj-y += l2switch.o obj-$(CONFIG_ARCH_MVFA5) += clock.o mvf_suspend.o diff --git a/arch/arm/mach-mvf/mvf_sema4.c b/arch/arm/mach-mvf/mvf_sema4.c new file mode 100644 index 000000000000..311b56a69d73 --- /dev/null +++ b/arch/arm/mach-mvf/mvf_sema4.c @@ -0,0 +1,234 @@ +/* +* header goes here +*/ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#define NUM_GATES 16 +#define MASK_FROM_GATE(gate_num) ((u32)(1 << (NUM_GATES*2 - 1 - idx[gate_num]))) + +#define THIS_CORE (0) +#define LOCK_VALUE (THIS_CORE + 1) + +#define SEMA4_CP0INE (MVF_SEMA4_BASE_ADDR + 0x40) +#define SEMA4_CP0NTF (MVF_SEMA4_BASE_ADDR + 0x80) + +//#if 0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +//#endif + +#include + +// ************************************ Local Data ************************************************* + +static MVF_SEMA4* gates[NUM_GATES]; + +static bool initialized = false; + +// account for the way the bits are set / returned in CP0INE and CP0NTF +static const int idx[16] = {3, 2, 1, 0, 7, 6, 5, 4, 11, 10, 9, 8, 15, 14, 13, 12}; + + +// ************************************ Interrupt handler ************************************************* + +static irqreturn_t sema4_irq_handler(int irq, void *dev_id) +{ + int gate_num; + + u32 cp0ntf = readl(MVF_IO_ADDRESS(SEMA4_CP0NTF)); + + for(gate_num=0; gate_numuse_interrupts) + // wake up whoever was aiting + wake_up_interruptible(&(gates[gate_num]->wait_queue)); + } + } + } + + return IRQ_HANDLED; +} + +// ************************************ Utility functions ************************************************* + +static int find_sema4(MVF_SEMA4 *sema4) +{ + int i; + + for(i=0; i= NUM_GATES)) + return -EINVAL; + + if(gates[gate_num]) + return -EBUSY; + + *sema4_p = (MVF_SEMA4 *)kmalloc(sizeof(MVF_SEMA4), GFP_KERNEL); + if(*sema4_p == NULL) + return -ENOMEM; + + gates[gate_num] = *sema4_p; + (*sema4_p)->gate_num = gate_num; + (*sema4_p)->use_interrupts = use_interrupts; + + if(use_interrupts) + { + init_waitqueue_head(&((*sema4_p)->wait_queue)); + local_irq_save(irq_flags); + cp0ine = readl(MVF_IO_ADDRESS(SEMA4_CP0INE)); + cp0ine |= MASK_FROM_GATE(gate_num); + writel(cp0ine, MVF_IO_ADDRESS(SEMA4_CP0INE)); + local_irq_restore(irq_flags); + } + + return 0; +} + +int mvf_sema4_deassign(MVF_SEMA4 *sema4) +{ + u32 cp0ine; + unsigned long irq_flags; + + int gate_num = find_sema4(sema4); + if(gate_num < 0) + return gate_num; + + if(sema4->use_interrupts) + { + local_irq_save(irq_flags); + cp0ine = readl(MVF_IO_ADDRESS(SEMA4_CP0INE)); + cp0ine &= ~MASK_FROM_GATE(gate_num); + writel(cp0ine, MVF_IO_ADDRESS(SEMA4_CP0INE)); + local_irq_restore(irq_flags); + } + + kfree(sema4); + gates[gate_num] = NULL; + + return 0; +} + +int mvf_sema4_lock(MVF_SEMA4 *sema4, unsigned int timeout_us) +{ + int retval; + int gate_num = find_sema4(sema4); + if(gate_num < 0) + return gate_num; + + // cant use timeouts if not using interruppts + // TODO use spin lock if not using interrupts + if((!sema4->use_interrupts) && timeout_us) + return -EINVAL; + + // try to grab it + writeb(LOCK_VALUE, MVF_IO_ADDRESS(MVF_SEMA4_BASE_ADDR) + gate_num); + if(readb(MVF_IO_ADDRESS(MVF_SEMA4_BASE_ADDR) + gate_num) == LOCK_VALUE) + return 0; + + // no timeout, fail + if(!timeout_us) + return -EBUSY; + + // wait forever? + if(timeout_us == 0xffffffff) + { + if(wait_event_interruptible(sema4->wait_queue, (readb(MVF_IO_ADDRESS(MVF_SEMA4_BASE_ADDR) + gate_num) == LOCK_VALUE))) + return -ERESTARTSYS; + } + else + { + // return: 0 = timeout, >0 = woke up with that many jiffies left, <0 = error + retval = wait_event_interruptible_timeout(sema4->wait_queue, + (readb(MVF_IO_ADDRESS(MVF_SEMA4_BASE_ADDR) + gate_num) == LOCK_VALUE), + usecs_to_jiffies(timeout_us)); + if(retval == 0) + return -ETIME; + else if(retval < 0) + return retval; + } + + return 0; +} + +int mvf_sema4_unlock(MVF_SEMA4 *sema4) +{ + int gate_num = find_sema4(sema4); + if(gate_num < 0) + return gate_num; + + // unlock it + writeb(0, MVF_IO_ADDRESS(MVF_SEMA4_BASE_ADDR) + gate_num); + + return 0; +} + diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 71b8cd4f8a3e..7741e8036997 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -52,6 +52,7 @@ #include #include #include +#include /** Defines ******************************************************************** *******************************************************************************/ @@ -122,6 +123,8 @@ static u16 __initdata i2c_clk_div[60][2] = { { 2304, 0x3C }, { 2560, 0x3D }, { 3072, 0x3E }, { 3584, 0x7A }, { 3840, 0x3F }, { 4096, 0x7B }, { 5120, 0x7D }, { 6144, 0x7E }, }; + +static MVF_SEMA4* sema4; #else static u16 __initdata i2c_clk_div[50][2] = { { 22, 0x20 }, { 24, 0x21 }, { 26, 0x22 }, { 28, 0x23 }, @@ -152,6 +155,7 @@ struct imx_i2c_struct { unsigned int ifdr; /* IMX_I2C_IFDR */ }; + /** Functions for IMX I2C adapter driver *************************************** *******************************************************************************/ @@ -434,6 +438,12 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter, dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); +#ifdef CONFIG_ARCH_MVF + result = mvf_sema4_lock(sema4, 1000000); + if(result) + return result; +#endif + /* Start I2C transfer */ result = i2c_imx_start(i2c_imx); if (result) @@ -482,6 +492,10 @@ fail0: /* Stop I2C transfer */ i2c_imx_stop(i2c_imx); +#ifdef CONFIG_ARCH_MVF + mvf_sema4_unlock(sema4); +#endif + dev_dbg(&i2c_imx->adapter.dev, "<%s> exit with: %s: %d\n", __func__, (result < 0) ? "error" : "success msg", (result < 0) ? result : num); @@ -605,6 +619,14 @@ static int __init i2c_imx_probe(struct platform_device *pdev) /* Set up platform driver data */ platform_set_drvdata(pdev, i2c_imx); +#ifdef CONFIG_ARCH_MVF + // make sure not in use by MQX + if(mvf_sema4_assign(3, true, &sema4)) { + dev_err(&pdev->dev, "could not grab MQX semaphore\n"); + goto fail5; + } +#endif + dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d\n", i2c_imx->irq); dev_dbg(&i2c_imx->adapter.dev, "device resources from 0x%x to 0x%x\n", i2c_imx->res->start, i2c_imx->res->end); diff --git a/include/linux/mvf_sema4.h b/include/linux/mvf_sema4.h new file mode 100644 index 000000000000..898065afb23f --- /dev/null +++ b/include/linux/mvf_sema4.h @@ -0,0 +1,15 @@ +#ifndef __MVF_SEMA4__ +#define __MVF_SEMA4__ + +typedef struct mvf_sema4_handle_struct { + int gate_num; + int use_interrupts; + wait_queue_head_t wait_queue; +} MVF_SEMA4; + +int mvf_sema4_assign(int gate_num, bool use_interrupts, MVF_SEMA4** sema4_p); +int mvf_sema4_deassign(MVF_SEMA4 *sema4); +int mvf_sema4_lock(MVF_SEMA4 *sema4, unsigned int timeout_us); +int mvf_sema4_unlock(MVF_SEMA4 *sema4); + +#endif -- cgit v1.2.3