Re: [PATCH 4/5 v5] i2c: i2c-piix4: Use request_declared_muxed_region()

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On 12/18/2017 12:48 AM, Zoltan Boszormenyi wrote:
From: Böszörményi Zoltán <zboszor@xxxxx>

Use the new request_declared_muxed_region() macro to
synchronize access to the I/O port pair 0xcd6 / 0xcd7.

At the same time, remove the long lifetime request_region()
call to reserve these I/O ports, so the sp5100_tco watchdog
driver can also load.

This fixes an old regression in Linux 4.4-rc4, caused by
commit 2fee61d22e60 ("i2c: piix4: Add support for multiplexed
main adapter in SB800")

v1: Started with a common mutex in a C source file.

v2: Referenced to common mutex from drivers/usb/host/pci-quirks.c

v3: Switched to using the new request_declared_muxed_region
     macro.

v4: Fixed checkpatch.pl warnings and use the new
     release_declared_region() macro.

v5: Rebased for 4.15-rc4
     Use struct i2c_algorithm pointer directly instead of
     a bool to select the proper algo.

This change makes sense, but it should be a separate patch.

Guenter


Signed-off-by: Zoltán Böszörményi <zboszor@xxxxx>
---
  drivers/i2c/busses/i2c-piix4.c | 51 +++++++++++++++---------------------------
  1 file changed, 18 insertions(+), 33 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 462948e2c535..1846d9ea7d27 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -153,10 +153,11 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
/*
   * SB800 globals
- * piix4_mutex_sb800 protects piix4_port_sel_sb800 and the pair
+ * request_declared_muxed_region() protects piix4_port_sel_sb800 and the pair
   * of I/O ports at SB800_PIIX4_SMB_IDX.
   */
-static DEFINE_MUTEX(piix4_mutex_sb800);
+static struct resource sb800_res = DEFINE_RES_IO_NAMED(SB800_PIIX4_SMB_IDX, 2,
+						 "i2c-piix4");
  static u8 piix4_port_sel_sb800;
  static u8 piix4_port_mask_sb800;
  static u8 piix4_port_shift_sb800;
@@ -169,7 +170,6 @@ struct i2c_piix4_adapdata {
  	unsigned short smba;
/* SB800 */
-	bool sb800_main;
  	bool notify_imc;
  	u8 port;		/* Port number, shifted */
  };
@@ -298,12 +298,12 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
  	else
  		smb_en = (aux) ? 0x28 : 0x2c;
- mutex_lock(&piix4_mutex_sb800);
+	request_declared_muxed_region(&sb800_res);
  	outb_p(smb_en, SB800_PIIX4_SMB_IDX);
  	smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
  	outb_p(smb_en + 1, SB800_PIIX4_SMB_IDX);
  	smba_en_hi = inb_p(SB800_PIIX4_SMB_IDX + 1);
-	mutex_unlock(&piix4_mutex_sb800);
+	release_declared_region(&sb800_res);
if (!smb_en) {
  		smb_en_status = smba_en_lo & 0x10;
@@ -373,7 +373,7 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
  			break;
  		}
  	} else {
-		mutex_lock(&piix4_mutex_sb800);
+		request_declared_muxed_region(&sb800_res);
  		outb_p(SB800_PIIX4_PORT_IDX_SEL, SB800_PIIX4_SMB_IDX);
  		port_sel = inb_p(SB800_PIIX4_SMB_IDX + 1);
  		piix4_port_sel_sb800 = (port_sel & 0x01) ?
@@ -381,7 +381,7 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
  				       SB800_PIIX4_PORT_IDX;
  		piix4_port_mask_sb800 = SB800_PIIX4_PORT_IDX_MASK;
  		piix4_port_shift_sb800 = SB800_PIIX4_PORT_IDX_SHIFT;
-		mutex_unlock(&piix4_mutex_sb800);
+		release_declared_region(&sb800_res);
  	}
dev_info(&PIIX4_dev->dev,
@@ -679,7 +679,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
  	u8 port;
  	int retval;
- mutex_lock(&piix4_mutex_sb800);
+	request_declared_muxed_region(&sb800_res);
/* Request the SMBUS semaphore, avoid conflicts with the IMC */
  	smbslvcnt  = inb_p(SMBSLVCNT);
@@ -695,7 +695,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
  	} while (--retries);
  	/* SMBus is still owned by the IMC, we give up */
  	if (!retries) {
-		mutex_unlock(&piix4_mutex_sb800);
+		release_declared_region(&sb800_res);
  		return -EBUSY;
  	}
@@ -753,7 +753,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
  	if ((size == I2C_SMBUS_BLOCK_DATA) && adapdata->notify_imc)
  		piix4_imc_wakeup();
- mutex_unlock(&piix4_mutex_sb800);
+	release_declared_region(&sb800_res);
return retval;
  }
@@ -804,7 +804,8 @@ static struct i2c_adapter *piix4_main_adapters[PIIX4_MAX_ADAPTERS];
  static struct i2c_adapter *piix4_aux_adapter;
static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
-			     bool sb800_main, u8 port, bool notify_imc,
+			     struct i2c_algorithm *algo,
+			     u8 port, bool notify_imc,
  			     const char *name, struct i2c_adapter **padap)
  {
  	struct i2c_adapter *adap;
@@ -819,8 +820,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
adap->owner = THIS_MODULE;
  	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
-	adap->algo = sb800_main ? &piix4_smbus_algorithm_sb800
-				: &smbus_algorithm;
+	adap->algo = algo;
adapdata = kzalloc(sizeof(*adapdata), GFP_KERNEL);
  	if (adapdata == NULL) {
@@ -830,7 +830,6 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
  	}
adapdata->smba = smba;
-	adapdata->sb800_main = sb800_main;
  	adapdata->port = port << piix4_port_shift_sb800;
  	adapdata->notify_imc = notify_imc;
@@ -862,7 +861,9 @@ static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba,
  	int retval;
for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
-		retval = piix4_add_adapter(dev, smba, true, port, notify_imc,
+		retval = piix4_add_adapter(dev, smba,
+					   &piix4_smbus_algorithm_sb800,
+					   port, notify_imc,
  					   piix4_main_port_names_sb800[port],
  					   &piix4_main_adapters[port]);
  		if (retval < 0)
@@ -899,13 +900,6 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
  		bool notify_imc = false;
  		is_sb800 = true;
- if (!request_region(SB800_PIIX4_SMB_IDX, 2, "smba_idx")) {
-			dev_err(&dev->dev,
-			"SMBus base address index region 0x%x already in use!\n",
-			SB800_PIIX4_SMB_IDX);
-			return -EBUSY;
-		}
-
  		if (dev->vendor == PCI_VENDOR_ID_AMD &&
  		    dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) {
  			u8 imc;
@@ -922,27 +916,24 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
/* base address location etc changed in SB800 */
  		retval = piix4_setup_sb800(dev, id, 0);
-		if (retval < 0) {
-			release_region(SB800_PIIX4_SMB_IDX, 2);
+		if (retval < 0)
  			return retval;
-		}
/*
  		 * Try to register multiplexed main SMBus adapter,
  		 * give up if we can't
  		 */
  		retval = piix4_add_adapters_sb800(dev, retval, notify_imc);
-		if (retval < 0) {
-			release_region(SB800_PIIX4_SMB_IDX, 2);
+		if (retval < 0)
  			return retval;
-		}
  	} else {
  		retval = piix4_setup(dev, id);
  		if (retval < 0)
  			return retval;
/* Try to register main SMBus adapter, give up if we can't */
-		retval = piix4_add_adapter(dev, retval, false, 0, false, "",
+		retval = piix4_add_adapter(dev, retval,
+					   &smbus_algorithm, 0, false, "",
  					   &piix4_main_adapters[0]);
  		if (retval < 0)
  			return retval;
@@ -983,11 +974,8 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
if (adapdata->smba) {
  		i2c_del_adapter(adap);
-		if (adapdata->port == (0 << piix4_port_shift_sb800)) {
+		if (adapdata->port == (0 << piix4_port_shift_sb800))
  			release_region(adapdata->smba, SMBIOSIZE);
-			if (adapdata->sb800_main)
-				release_region(SB800_PIIX4_SMB_IDX, 2);
-		}
  		kfree(adapdata);
  		kfree(adap);
  	}


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