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Diffstat (limited to 'drivers/i2c/busses')
-rw-r--r--drivers/i2c/busses/i2c-i801.c99
1 files changed, 95 insertions, 4 deletions
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index a1ce4e68b49a..bcce18dfcc39 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -60,10 +60,12 @@
Block process call transaction no
I2C block read transaction yes (doesn't use the block buffer)
Slave mode no
+ Interrupt processing yes
See the file Documentation/i2c/busses/i2c-i801 for details.
*/
+#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/kernel.h>
@@ -76,6 +78,7 @@
#include <linux/io.h>
#include <linux/dmi.h>
#include <linux/slab.h>
+#include <linux/wait.h>
/* I801 SMBus address offsets */
#define SMBHSTSTS(p) (0 + (p)->smba)
@@ -91,8 +94,12 @@
/* PCI Address Constants */
#define SMBBAR 4
+#define SMBPCISTS 0x006
#define SMBHSTCFG 0x040
+/* Host status bits for SMBPCISTS */
+#define SMBPCISTS_INTS 0x08
+
/* Host configuration bits for SMBHSTCFG */
#define SMBHSTCFG_HST_EN 1
#define SMBHSTCFG_SMB_SMI_EN 2
@@ -155,6 +162,10 @@ struct i801_priv {
unsigned char original_hstcfg;
struct pci_dev *pci_dev;
unsigned int features;
+
+ /* isr processing */
+ wait_queue_head_t waitq;
+ u8 status;
};
static struct pci_driver i801_driver;
@@ -163,6 +174,7 @@ static struct pci_driver i801_driver;
#define FEATURE_BLOCK_BUFFER (1 << 1)
#define FEATURE_BLOCK_PROC (1 << 2)
#define FEATURE_I2C_BLOCK_READ (1 << 3)
+#define FEATURE_IRQ (1 << 4)
/* Not really a feature, but it's convenient to handle it as such */
#define FEATURE_IDF (1 << 15)
@@ -171,6 +183,7 @@ static const char *i801_feature_names[] = {
"Block buffer",
"Block process call",
"I2C block read",
+ "Interrupt",
};
static unsigned int disable_features;
@@ -215,7 +228,12 @@ static int i801_check_post(struct i801_priv *priv, int status)
{
int result = 0;
- /* If the SMBus is still busy, we give up */
+ /*
+ * If the SMBus is still busy, we give up
+ * Note: This timeout condition only happens when using polling
+ * transactions. For interrupt operation, NAK/timeout is indicated by
+ * DEV_ERR.
+ */
if (unlikely(status < 0)) {
dev_err(&priv->pci_dev->dev, "Transaction timeout\n");
/* try to stop the current command */
@@ -305,6 +323,14 @@ static int i801_transaction(struct i801_priv *priv, int xact)
if (result < 0)
return result;
+ if (priv->features & FEATURE_IRQ) {
+ outb_p(xact | SMBHSTCNT_INTREN | SMBHSTCNT_START,
+ SMBHSTCNT(priv));
+ wait_event(priv->waitq, (status = priv->status));
+ priv->status = 0;
+ return i801_check_post(priv, status);
+ }
+
/* the current contents of SMBHSTCNT can be overwritten, since PEC,
* SMBSCMD are passed in xact */
outb_p(xact | SMBHSTCNT_START, SMBHSTCNT(priv));
@@ -348,6 +374,44 @@ static int i801_block_transaction_by_block(struct i801_priv *priv,
}
/*
+ * i801 signals transaction completion with one of these interrupts:
+ * INTR - Success
+ * DEV_ERR - Invalid command, NAK or communication timeout
+ * BUS_ERR - SMI# transaction collision
+ * FAILED - transaction was canceled due to a KILL request
+ * When any of these occur, update ->status and wake up the waitq.
+ * ->status must be cleared before kicking off the next transaction.
+ */
+static irqreturn_t i801_isr(int irq, void *dev_id)
+{
+ struct i801_priv *priv = dev_id;
+ u16 pcists;
+ u8 status;
+
+ /* Confirm this is our interrupt */
+ pci_read_config_word(priv->pci_dev, SMBPCISTS, &pcists);
+ if (!(pcists & SMBPCISTS_INTS))
+ return IRQ_NONE;
+
+ status = inb_p(SMBHSTSTS(priv));
+ if (status != 0x42)
+ dev_dbg(&priv->pci_dev->dev, "irq: status = %02x\n", status);
+
+ /*
+ * Clear irq sources and report transaction result.
+ * ->status must be cleared before the next transaction is started.
+ */
+ status &= SMBHSTSTS_INTR | STATUS_ERROR_FLAGS;
+ if (status) {
+ outb_p(status, SMBHSTSTS(priv));
+ priv->status |= status;
+ wake_up(&priv->waitq);
+ }
+
+ return IRQ_HANDLED;
+}
+
+/*
* For "byte-by-byte" block transactions:
* I2C write uses cmd=I801_BLOCK_DATA, I2C_EN=1
* I2C read uses cmd=I801_I2C_BLOCK_DATA
@@ -799,6 +863,10 @@ static int __devinit i801_probe(struct pci_dev *dev,
break;
}
+ /* IRQ processing only tested on CougarPoint PCH */
+ if (dev->device == PCI_DEVICE_ID_INTEL_COUGARPOINT_SMBUS)
+ priv->features |= FEATURE_IRQ;
+
/* Disable features on user request */
for (i = 0; i < ARRAY_SIZE(i801_feature_names); i++) {
if (priv->features & disable_features & (1 << i))
@@ -846,16 +914,31 @@ static int __devinit i801_probe(struct pci_dev *dev,
}
pci_write_config_byte(priv->pci_dev, SMBHSTCFG, temp);
- if (temp & SMBHSTCFG_SMB_SMI_EN)
+ if (temp & SMBHSTCFG_SMB_SMI_EN) {
dev_dbg(&dev->dev, "SMBus using interrupt SMI#\n");
- else
+ /* Disable SMBus interrupt feature if SMBus using SMI# */
+ priv->features &= ~FEATURE_IRQ;
+ } else {
dev_dbg(&dev->dev, "SMBus using PCI Interrupt\n");
+ }
/* Clear special mode bits */
if (priv->features & (FEATURE_SMBUS_PEC | FEATURE_BLOCK_BUFFER))
outb_p(inb_p(SMBAUXCTL(priv)) &
~(SMBAUXCTL_CRC | SMBAUXCTL_E32B), SMBAUXCTL(priv));
+ if (priv->features & FEATURE_IRQ) {
+ init_waitqueue_head(&priv->waitq);
+
+ err = request_irq(dev->irq, i801_isr, IRQF_SHARED,
+ i801_driver.name, priv);
+ if (err) {
+ dev_err(&dev->dev, "Failed to allocate irq %d: %d\n",
+ dev->irq, err);
+ goto exit_release;
+ }
+ }
+
/* set up the sysfs linkage to our parent device */
priv->adapter.dev.parent = &dev->dev;
@@ -867,14 +950,18 @@ static int __devinit i801_probe(struct pci_dev *dev,
err = i2c_add_adapter(&priv->adapter);
if (err) {
dev_err(&dev->dev, "Failed to add SMBus adapter\n");
- goto exit_release;
+ goto exit_free_irq;
}
i801_probe_optional_slaves(priv);
pci_set_drvdata(dev, priv);
+
return 0;
+exit_free_irq:
+ if (priv->features & FEATURE_IRQ)
+ free_irq(dev->irq, priv);
exit_release:
pci_release_region(dev, SMBBAR);
exit:
@@ -888,7 +975,11 @@ static void __devexit i801_remove(struct pci_dev *dev)
i2c_del_adapter(&priv->adapter);
pci_write_config_byte(dev, SMBHSTCFG, priv->original_hstcfg);
+
+ if (priv->features & FEATURE_IRQ)
+ free_irq(dev->irq, priv);
pci_release_region(dev, SMBBAR);
+
pci_set_drvdata(dev, NULL);
kfree(priv);
/*
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-18 15:08:47 +0300