Re: [PATCH v2 09/11] mfd: twl-core: Collect global variables behind one private structure (global)

[Jon Hunter <jon-hunter@ti.com>]

On 01/16/2013 07:53 AM, Peter Ujfalusi wrote:
> Gather the global variables under a single structure and allocate it with
> devm_kzalloc(). It is easier to see them and if in the future we try to add
> support for multiple instance of twl in the system it is going to be much
> simpler.
> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> ---
>  drivers/mfd/twl-core.c | 104 +++++++++++++++++++++++++++----------------------
>  1 file changed, 57 insertions(+), 47 deletions(-)
> 
> diff --git a/drivers/mfd/twl-core.c b/drivers/mfd/twl-core.c
> index 1827088..e2895a4 100644
> --- a/drivers/mfd/twl-core.c
> +++ b/drivers/mfd/twl-core.c
> @@ -141,33 +141,28 @@
>  
>  /*----------------------------------------------------------------------*/
>  
> -/* is driver active, bound to a chip? */
> -static bool inuse;
> -
> -/* TWL IDCODE Register value */
> -static u32 twl_idcode;
> -
> -static unsigned int twl_id;
> -unsigned int twl_rev(void)
> -{
> -	return twl_id;
> -}
> -EXPORT_SYMBOL(twl_rev);
> -
>  /* Structure for each TWL4030/TWL6030 Slave */
>  struct twl_client {
>  	struct i2c_client *client;
>  	struct regmap *regmap;
>  };
>  
> -static struct twl_client *twl_modules;
> -
>  /* mapping the module id to slave id and base address */
>  struct twl_mapping {
>  	unsigned char sid;	/* Slave ID */
>  	unsigned char base;	/* base address */
>  };
> -static struct twl_mapping *twl_map;
> +
> +struct twl_private {
> +	bool ready; /* The core driver is ready to be used */
> +	u32 twl_idcode; /* TWL IDCODE Register value */
> +	unsigned int twl_id;
> +
> +	struct twl_mapping *twl_map;
> +	struct twl_client *twl_modules;
> +};
> +
> +static struct twl_private *twl_priv;
>  
>  static struct twl_mapping twl4030_map[] = {
>  	/*
> @@ -300,6 +295,12 @@ static inline int twl_get_last_module(void)
>  
>  /* Exported Functions */
>  
> +unsigned int twl_rev(void)
> +{
> +	return twl_priv ? twl_priv->twl_id : 0;
> +}
> +EXPORT_SYMBOL(twl_rev);
> +
>  /**
>   * twl_i2c_write - Writes a n bit register in TWL4030/TWL5030/TWL60X0
>   * @mod_no: module number
> @@ -322,16 +323,17 @@ int twl_i2c_write(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes)
>  		pr_err("%s: invalid module number %d\n", DRIVER_NAME, mod_no);
>  		return -EPERM;
>  	}
> -	if (unlikely(!inuse)) {
> +	if (unlikely(!twl_priv->ready)) {

This is causing the kernel to panic on all my omap2 boards when booting linux-next
because twl_priv is not initialised yet.

>  		pr_err("%s: not initialized\n", DRIVER_NAME);
>  		return -EPERM;
>  	}
>  
> -	sid = twl_map[mod_no].sid;
> -	twl = &twl_modules[sid];
> +	sid = twl_priv->twl_map[mod_no].sid;
> +	twl = &twl_priv->twl_modules[sid];
>  
> -	ret = regmap_bulk_write(twl->regmap, twl_map[mod_no].base + reg,
> -				value, num_bytes);
> +	ret = regmap_bulk_write(twl->regmap,
> +				twl_priv->twl_map[mod_no].base + reg, value,
> +				num_bytes);
>  
>  	if (ret)
>  		pr_err("%s: Write failed (mod %d, reg 0x%02x count %d)\n",
> @@ -360,16 +362,17 @@ int twl_i2c_read(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes)
>  		pr_err("%s: invalid module number %d\n", DRIVER_NAME, mod_no);
>  		return -EPERM;
>  	}
> -	if (unlikely(!inuse)) {
> +	if (unlikely(!twl_priv->ready)) {

Same problem here. 

Here is a fix ...

>From 141fcbbdee6bdc14d5a444ff20fad6b3440215dc Mon Sep 17 00:00:00 2001
From: Jon Hunter <jon-hunter@ti.com>
Date: Fri, 8 Feb 2013 12:42:20 -0600
Subject: [PATCH] ARM: OMAP2+: Fix kernel panic on boot

Commit 8a6aaa3 (mfd: twl-core: Collect global variables behind one
private structure (global)) removed the variable "inuse" that is used
to determine if the device has been initialised and now use the
twl_priv structure instead. This is causing the kernel to panic on all
OMAP2+ devices, because we try to access the twl_priv->ready member
before checking if twl_priv is initialised. Fix this and move this test
to the beginning of the twl_i2c_read/write function because
twl_get_last_module() also uses the twl_priv structure.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
---
 drivers/mfd/twl-core.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/mfd/twl-core.c b/drivers/mfd/twl-core.c
index 557f9ee..89ab4d9 100644
--- a/drivers/mfd/twl-core.c
+++ b/drivers/mfd/twl-core.c
@@ -316,12 +316,12 @@ int twl_i2c_write(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes)
 	int sid;
 	struct twl_client *twl;
 
-	if (unlikely(mod_no >= twl_get_last_module())) {
-		pr_err("%s: invalid module number %d\n", DRIVER_NAME, mod_no);
+	if (unlikely(!twl_priv || !twl_priv->ready)) {
+		pr_err("%s: not initialized\n", DRIVER_NAME);
 		return -EPERM;
 	}
-	if (unlikely(!twl_priv->ready)) {
-		pr_err("%s: not initialized\n", DRIVER_NAME);
+	if (unlikely(mod_no >= twl_get_last_module())) {
+		pr_err("%s: invalid module number %d\n", DRIVER_NAME, mod_no);
 		return -EPERM;
 	}
 
@@ -355,12 +355,12 @@ int twl_i2c_read(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes)
 	int sid;
 	struct twl_client *twl;
 
-	if (unlikely(mod_no >= twl_get_last_module())) {
-		pr_err("%s: invalid module number %d\n", DRIVER_NAME, mod_no);
+	if (unlikely(!twl_priv || !twl_priv->ready)) {
+		pr_err("%s: not initialized\n", DRIVER_NAME);
 		return -EPERM;
 	}
-	if (unlikely(!twl_priv->ready)) {
-		pr_err("%s: not initialized\n", DRIVER_NAME);
+	if (unlikely(mod_no >= twl_get_last_module())) {
+		pr_err("%s: invalid module number %d\n", DRIVER_NAME, mod_no);
 		return -EPERM;
 	}
 
-- 
1.7.10.4