[PATCH v2 00/11] Clean up Tegra20 cpufreq driver

[PATCH v2 00/11] Clean up Tegra20 cpufreq driver

[Dmitry Osipenko]

Hello,

Recently Peter Geis (who is working on Tegra30 cpufreq driver) asked me how
tegra20-cpufreq driver is getting loaded. After taking a look at the code
it became apparent that the drivers code has been rusted a tad and so this
series is intended to refresh the drivers code by disallowing module to be
loaded on non-Tegra20 machines, by cleaning whitespaces in the code, removing
dead EMC code and in the end by allowing tegra20-cpufreq to be built as a
loadable module.

Changelog:

v2:
	- Added the new patch to the series: "Remove unnecessary parentheses",
	  please review.

	- Addressed review comments to the v1 of the series:

	1) Kept undeleted necessary headers in the "Clean up included headers"
	   patch as per Viresh's Kumar request.

	2) Renamed tegra20_cpufreq_data to tegra20_cpufreq and moved cpufreq
	   driver structure to the tegra20_cpufreq as per Thierry's Reding
	   request.

	- Dropped "ARM: tegra: Create platform device for tegra20-cpufreq driver"
	  patch from the series as Thierry already applied it and submitted
	  in the "ARM: tegra: Core changes for v4.18-rc1" pull request.

Dmitry Osipenko (11):
  cpufreq: tegra20: Change module description
  cpufreq: tegra20: Clean up whitespaces in the code
  cpufreq: tegra20: Clean up included headers
  cpufreq: tegra20: Remove EMC clock usage
  cpufreq: tegra20: Release clocks properly
  cpufreq: tegra20: Remove unneeded check in tegra_cpu_init
  cpufreq: tegra20: Remove unnecessary parentheses
  cpufreq: tegra20: Remove unneeded variable initialization
  cpufreq: tegra20: Check if this is Tegra20 machine
  cpufreq: tegra20: Allow cpufreq driver to be built as loadable module
  cpufreq: tegra20: Wrap cpufreq into platform driver

 drivers/cpufreq/Kconfig.arm       |   2 +-
 drivers/cpufreq/tegra20-cpufreq.c | 200 ++++++++++++++++--------------
 2 files changed, 111 insertions(+), 91 deletions(-)

-- 
2.17.0

[PATCH v2 01/11] cpufreq: tegra20: Change module description

[Dmitry Osipenko]

Change module description to be in line with the other Tegra drivers, just
for consistency.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index 2bd62845e9d5..10793498355e 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -210,7 +210,7 @@ static void __exit tegra_cpufreq_exit(void)
 
 
 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
-MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
+MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
 MODULE_LICENSE("GPL");
 module_init(tegra_cpufreq_init);
 module_exit(tegra_cpufreq_exit);
-- 
2.17.0

[PATCH v2 02/11] cpufreq: tegra20: Clean up whitespaces in the code

[Dmitry Osipenko]

Remove unneeded blank line and replace whitespaces with a tab in the code
for consistency.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index 10793498355e..dd8a76a64a8e 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -203,12 +203,11 @@ static int __init tegra_cpufreq_init(void)
 
 static void __exit tegra_cpufreq_exit(void)
 {
-        cpufreq_unregister_driver(&tegra_cpufreq_driver);
+	cpufreq_unregister_driver(&tegra_cpufreq_driver);
 	clk_put(emc_clk);
 	clk_put(cpu_clk);
 }
 
-
 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
 MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
 MODULE_LICENSE("GPL");
-- 
2.17.0

[PATCH v2 03/11] cpufreq: tegra20: Clean up included headers

[Dmitry Osipenko]

Remove unused/unneeded headers and sort them in the alphabet order.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index dd8a76a64a8e..bec1a50a8138 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -16,16 +16,12 @@
  *
  */
 
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/types.h>
-#include <linux/sched.h>
+#include <linux/clk.h>
 #include <linux/cpufreq.h>
-#include <linux/delay.h>
-#include <linux/init.h>
 #include <linux/err.h>
-#include <linux/clk.h>
-#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
 
 static struct cpufreq_frequency_table freq_table[] = {
 	{ .frequency = 216000 },
-- 
2.17.0

Re: [PATCH v2 03/11] cpufreq: tegra20: Clean up included headers

[Viresh Kumar]

On 18-05-18, 23:06, Dmitry Osipenko wrote:
> Remove unused/unneeded headers and sort them in the alphabet order.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> Acked-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/cpufreq/tegra20-cpufreq.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
> index dd8a76a64a8e..bec1a50a8138 100644
> --- a/drivers/cpufreq/tegra20-cpufreq.c
> +++ b/drivers/cpufreq/tegra20-cpufreq.c
> @@ -16,16 +16,12 @@
>   *
>   */
>  
> -#include <linux/kernel.h>
> -#include <linux/module.h>
> -#include <linux/types.h>
> -#include <linux/sched.h>
> +#include <linux/clk.h>
>  #include <linux/cpufreq.h>
> -#include <linux/delay.h>
> -#include <linux/init.h>
>  #include <linux/err.h>
> -#include <linux/clk.h>
> -#include <linux/io.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
>  
>  static struct cpufreq_frequency_table freq_table[] = {
>  	{ .frequency = 216000 },

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh

[PATCH v2 04/11] cpufreq: tegra20: Remove EMC clock usage

[Dmitry Osipenko]

The EMC driver has been gone 4 years ago, since the commit a7cbe92cef27
("ARM: tegra: remove tegra EMC scaling driver"). Remove the EMC clock
usage as it does nothing. We may consider re-implementing the EMC scaling
later, probably using PM Memory Bandwidth QoS API.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 22 ----------------------
 1 file changed, 22 deletions(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index bec1a50a8138..4b09a8b410c4 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -40,7 +40,6 @@ static struct cpufreq_frequency_table freq_table[] = {
 static struct clk *cpu_clk;
 static struct clk *pll_x_clk;
 static struct clk *pll_p_clk;
-static struct clk *emc_clk;
 static bool pll_x_prepared;
 
 static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
@@ -91,17 +90,6 @@ static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
 	unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
 	int ret = 0;
 
-	/*
-	 * Vote on memory bus frequency based on cpu frequency
-	 * This sets the minimum frequency, display or avp may request higher
-	 */
-	if (rate >= 816000)
-		clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
-	else if (rate >= 456000)
-		clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
-	else
-		clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
-
 	/*
 	 * target freq == pll_p, don't need to take extra reference to pll_x_clk
 	 * as it isn't used anymore.
@@ -137,14 +125,12 @@ static int tegra_cpu_init(struct cpufreq_policy *policy)
 	if (policy->cpu >= NUM_CPUS)
 		return -EINVAL;
 
-	clk_prepare_enable(emc_clk);
 	clk_prepare_enable(cpu_clk);
 
 	/* FIXME: what's the actual transition time? */
 	ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 	if (ret) {
 		clk_disable_unprepare(cpu_clk);
-		clk_disable_unprepare(emc_clk);
 		return ret;
 	}
 
@@ -156,7 +142,6 @@ static int tegra_cpu_init(struct cpufreq_policy *policy)
 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 {
 	clk_disable_unprepare(cpu_clk);
-	clk_disable_unprepare(emc_clk);
 	return 0;
 }
 
@@ -188,19 +173,12 @@ static int __init tegra_cpufreq_init(void)
 	if (IS_ERR(pll_p_clk))
 		return PTR_ERR(pll_p_clk);
 
-	emc_clk = clk_get_sys("cpu", "emc");
-	if (IS_ERR(emc_clk)) {
-		clk_put(cpu_clk);
-		return PTR_ERR(emc_clk);
-	}
-
 	return cpufreq_register_driver(&tegra_cpufreq_driver);
 }
 
 static void __exit tegra_cpufreq_exit(void)
 {
 	cpufreq_unregister_driver(&tegra_cpufreq_driver);
-	clk_put(emc_clk);
 	clk_put(cpu_clk);
 }
 
-- 
2.17.0

[PATCH v2 05/11] cpufreq: tegra20: Release clocks properly

[Dmitry Osipenko]

Properly put requested clocks in the module init/exit code.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index 4b09a8b410c4..ea186d3f0faf 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -161,24 +161,45 @@ static struct cpufreq_driver tegra_cpufreq_driver = {
 
 static int __init tegra_cpufreq_init(void)
 {
+	int err;
+
 	cpu_clk = clk_get_sys(NULL, "cclk");
 	if (IS_ERR(cpu_clk))
 		return PTR_ERR(cpu_clk);
 
 	pll_x_clk = clk_get_sys(NULL, "pll_x");
-	if (IS_ERR(pll_x_clk))
-		return PTR_ERR(pll_x_clk);
+	if (IS_ERR(pll_x_clk)) {
+		err = PTR_ERR(pll_x_clk);
+		goto put_cpu;
+	}
 
 	pll_p_clk = clk_get_sys(NULL, "pll_p");
-	if (IS_ERR(pll_p_clk))
-		return PTR_ERR(pll_p_clk);
+	if (IS_ERR(pll_p_clk)) {
+		err = PTR_ERR(pll_p_clk);
+		goto put_pll_x;
+	}
+
+	err = cpufreq_register_driver(&tegra_cpufreq_driver);
+	if (err)
+		goto put_pll_p;
+
+	return 0;
+
+put_pll_p:
+	clk_put(pll_p_clk);
+put_pll_x:
+	clk_put(pll_x_clk);
+put_cpu:
+	clk_put(cpu_clk);
 
-	return cpufreq_register_driver(&tegra_cpufreq_driver);
+	return err;
 }
 
 static void __exit tegra_cpufreq_exit(void)
 {
 	cpufreq_unregister_driver(&tegra_cpufreq_driver);
+	clk_put(pll_p_clk);
+	clk_put(pll_x_clk);
 	clk_put(cpu_clk);
 }
 
-- 
2.17.0

[PATCH v2 06/11] cpufreq: tegra20: Remove unneeded check in tegra_cpu_init

[Dmitry Osipenko]

Remove checking of the CPU number for consistency as it won't ever fail
unless there is a severe bug in the cpufreq core.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index ea186d3f0faf..df25e350c8e6 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -35,8 +35,6 @@ static struct cpufreq_frequency_table freq_table[] = {
 	{ .frequency = CPUFREQ_TABLE_END },
 };
 
-#define NUM_CPUS	2
-
 static struct clk *cpu_clk;
 static struct clk *pll_x_clk;
 static struct clk *pll_p_clk;
@@ -122,9 +120,6 @@ static int tegra_cpu_init(struct cpufreq_policy *policy)
 {
 	int ret;
 
-	if (policy->cpu >= NUM_CPUS)
-		return -EINVAL;
-
 	clk_prepare_enable(cpu_clk);
 
 	/* FIXME: what's the actual transition time? */
-- 
2.17.0

[PATCH v2 07/11] cpufreq: tegra20: Remove unnecessary parentheses

[Dmitry Osipenko]

Remove unnecessary parentheses as suggested by the checkpatch script.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index df25e350c8e6..4b85a6733533 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -50,7 +50,7 @@ static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
 	 * - we are already at it, i.e. policy->cur == ifreq
 	 * - index corresponds to ifreq
 	 */
-	if ((freq_table[index].frequency == ifreq) || (policy->cur == ifreq))
+	if (freq_table[index].frequency == ifreq || policy->cur == ifreq)
 		return 0;
 
 	return ifreq;
-- 
2.17.0

Re: [PATCH v2 07/11] cpufreq: tegra20: Remove unnecessary parentheses

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 347 bytes --]

On Fri, May 18, 2018 at 11:06:38PM +0300, Dmitry Osipenko wrote:
> Remove unnecessary parentheses as suggested by the checkpatch script.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/cpufreq/tegra20-cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Thierry Reding <treding@nvidia.com>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH v2 07/11] cpufreq: tegra20: Remove unnecessary parentheses

[Viresh Kumar]

On 18-05-18, 23:06, Dmitry Osipenko wrote:
> Remove unnecessary parentheses as suggested by the checkpatch script.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/cpufreq/tegra20-cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
> index df25e350c8e6..4b85a6733533 100644
> --- a/drivers/cpufreq/tegra20-cpufreq.c
> +++ b/drivers/cpufreq/tegra20-cpufreq.c
> @@ -50,7 +50,7 @@ static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
>  	 * - we are already at it, i.e. policy->cur == ifreq
>  	 * - index corresponds to ifreq
>  	 */
> -	if ((freq_table[index].frequency == ifreq) || (policy->cur == ifreq))
> +	if (freq_table[index].frequency == ifreq || policy->cur == ifreq)
>  		return 0;
>  
>  	return ifreq;

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh

[PATCH v2 08/11] cpufreq: tegra20: Remove unneeded variable initialization

[Dmitry Osipenko]

Remove unneeded variable initialization solely for consistency.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index 4b85a6733533..36075aee2ff2 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -86,7 +86,7 @@ static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
 {
 	unsigned long rate = freq_table[index].frequency;
 	unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
-	int ret = 0;
+	int ret;
 
 	/*
 	 * target freq == pll_p, don't need to take extra reference to pll_x_clk
-- 
2.17.0

[PATCH v2 09/11] cpufreq: tegra20: Check if this is Tegra20 machine

[Dmitry Osipenko]

Don't even try to request the clocks during of module initialization on
non-Tegra20 machines (this is the case for a multi-platform kernel) for
consistency.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/tegra20-cpufreq.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index 36075aee2ff2..7b425ebe81e7 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -21,6 +21,7 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/types.h>
 
 static struct cpufreq_frequency_table freq_table[] = {
@@ -158,6 +159,9 @@ static int __init tegra_cpufreq_init(void)
 {
 	int err;
 
+	if (!of_machine_is_compatible("nvidia,tegra20"))
+		return -ENODEV;
+
 	cpu_clk = clk_get_sys(NULL, "cclk");
 	if (IS_ERR(cpu_clk))
 		return PTR_ERR(cpu_clk);
-- 
2.17.0

[PATCH v2 10/11] cpufreq: tegra20: Allow cpufreq driver to be built as loadable module

[Dmitry Osipenko]

Nothing prevents Tegra20 CPUFreq module to be unloaded, hence allow it to
be built as a non-builtin kernel module.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Thierry Reding <treding@nvidia.com>
---
 drivers/cpufreq/Kconfig.arm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 96b35b8b3606..a8a2e210c624 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -264,7 +264,7 @@ config ARM_TANGO_CPUFREQ
 	default y
 
 config ARM_TEGRA20_CPUFREQ
-	bool "Tegra20 CPUFreq support"
+	tristate "Tegra20 CPUFreq support"
 	depends on ARCH_TEGRA
 	default y
 	help
-- 
2.17.0

[PATCH v2 11/11] cpufreq: tegra20: Wrap cpufreq into platform driver

[Dmitry Osipenko]

Currently tegra20-cpufreq kernel module isn't getting autoloaded because
there is no device associated with the module, this is one of two patches
that resolves the module autoloading. This patch adds a module alias that
will associate the tegra20-cpufreq kernel module with the platform device,
other patch will instantiate the actual platform device. And now it makes
sense to wrap cpufreq driver into a platform driver for consistency.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/tegra20-cpufreq.c | 145 ++++++++++++++++++------------
 1 file changed, 86 insertions(+), 59 deletions(-)

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
index 7b425ebe81e7..05f57dcd5215 100644
--- a/drivers/cpufreq/tegra20-cpufreq.c
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -21,7 +21,7 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/module.h>
-#include <linux/of.h>
+#include <linux/platform_device.h>
 #include <linux/types.h>
 
 static struct cpufreq_frequency_table freq_table[] = {
@@ -36,15 +36,20 @@ static struct cpufreq_frequency_table freq_table[] = {
 	{ .frequency = CPUFREQ_TABLE_END },
 };
 
-static struct clk *cpu_clk;
-static struct clk *pll_x_clk;
-static struct clk *pll_p_clk;
-static bool pll_x_prepared;
+struct tegra20_cpufreq {
+	struct device *dev;
+	struct cpufreq_driver driver;
+	struct clk *cpu_clk;
+	struct clk *pll_x_clk;
+	struct clk *pll_p_clk;
+	bool pll_x_prepared;
+};
 
 static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
 					   unsigned int index)
 {
-	unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
+	struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
+	unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000;
 
 	/*
 	 * Don't switch to intermediate freq if:
@@ -60,6 +65,7 @@ static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
 static int tegra_target_intermediate(struct cpufreq_policy *policy,
 				     unsigned int index)
 {
+	struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
 	int ret;
 
 	/*
@@ -72,21 +78,22 @@ static int tegra_target_intermediate(struct cpufreq_policy *policy,
 	 * Also, we wouldn't be using pll_x anymore and must not take extra
 	 * reference to it, as it can be disabled now to save some power.
 	 */
-	clk_prepare_enable(pll_x_clk);
+	clk_prepare_enable(cpufreq->pll_x_clk);
 
-	ret = clk_set_parent(cpu_clk, pll_p_clk);
+	ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk);
 	if (ret)
-		clk_disable_unprepare(pll_x_clk);
+		clk_disable_unprepare(cpufreq->pll_x_clk);
 	else
-		pll_x_prepared = true;
+		cpufreq->pll_x_prepared = true;
 
 	return ret;
 }
 
 static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
 {
+	struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
 	unsigned long rate = freq_table[index].frequency;
-	unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
+	unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000;
 	int ret;
 
 	/*
@@ -94,14 +101,14 @@ static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
 	 * as it isn't used anymore.
 	 */
 	if (rate == ifreq)
-		return clk_set_parent(cpu_clk, pll_p_clk);
+		return clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk);
 
-	ret = clk_set_rate(pll_x_clk, rate * 1000);
+	ret = clk_set_rate(cpufreq->pll_x_clk, rate * 1000);
 	/* Restore to earlier frequency on error, i.e. pll_x */
 	if (ret)
-		pr_err("Failed to change pll_x to %lu\n", rate);
+		dev_err(cpufreq->dev, "Failed to change pll_x to %lu\n", rate);
 
-	ret = clk_set_parent(cpu_clk, pll_x_clk);
+	ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_x_clk);
 	/* This shouldn't fail while changing or restoring */
 	WARN_ON(ret);
 
@@ -109,9 +116,9 @@ static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
 	 * Drop count to pll_x clock only if we switched to intermediate freq
 	 * earlier while transitioning to a target frequency.
 	 */
-	if (pll_x_prepared) {
-		clk_disable_unprepare(pll_x_clk);
-		pll_x_prepared = false;
+	if (cpufreq->pll_x_prepared) {
+		clk_disable_unprepare(cpufreq->pll_x_clk);
+		cpufreq->pll_x_prepared = false;
 	}
 
 	return ret;
@@ -119,91 +126,111 @@ static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
 
 static int tegra_cpu_init(struct cpufreq_policy *policy)
 {
+	struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
 	int ret;
 
-	clk_prepare_enable(cpu_clk);
+	clk_prepare_enable(cpufreq->cpu_clk);
 
 	/* FIXME: what's the actual transition time? */
 	ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 	if (ret) {
-		clk_disable_unprepare(cpu_clk);
+		clk_disable_unprepare(cpufreq->cpu_clk);
 		return ret;
 	}
 
-	policy->clk = cpu_clk;
+	policy->clk = cpufreq->cpu_clk;
 	policy->suspend_freq = freq_table[0].frequency;
 	return 0;
 }
 
 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 {
-	clk_disable_unprepare(cpu_clk);
+	struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
+
+	clk_disable_unprepare(cpufreq->cpu_clk);
 	return 0;
 }
 
-static struct cpufreq_driver tegra_cpufreq_driver = {
-	.flags			= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
-	.verify			= cpufreq_generic_frequency_table_verify,
-	.get_intermediate	= tegra_get_intermediate,
-	.target_intermediate	= tegra_target_intermediate,
-	.target_index		= tegra_target,
-	.get			= cpufreq_generic_get,
-	.init			= tegra_cpu_init,
-	.exit			= tegra_cpu_exit,
-	.name			= "tegra",
-	.attr			= cpufreq_generic_attr,
-	.suspend		= cpufreq_generic_suspend,
-};
-
-static int __init tegra_cpufreq_init(void)
+static int tegra20_cpufreq_probe(struct platform_device *pdev)
 {
+	struct tegra20_cpufreq *cpufreq;
 	int err;
 
-	if (!of_machine_is_compatible("nvidia,tegra20"))
-		return -ENODEV;
+	cpufreq = devm_kzalloc(&pdev->dev, sizeof(*cpufreq), GFP_KERNEL);
+	if (!cpufreq)
+		return -ENOMEM;
 
-	cpu_clk = clk_get_sys(NULL, "cclk");
-	if (IS_ERR(cpu_clk))
-		return PTR_ERR(cpu_clk);
+	cpufreq->cpu_clk = clk_get_sys(NULL, "cclk");
+	if (IS_ERR(cpufreq->cpu_clk))
+		return PTR_ERR(cpufreq->cpu_clk);
 
-	pll_x_clk = clk_get_sys(NULL, "pll_x");
-	if (IS_ERR(pll_x_clk)) {
-		err = PTR_ERR(pll_x_clk);
+	cpufreq->pll_x_clk = clk_get_sys(NULL, "pll_x");
+	if (IS_ERR(cpufreq->pll_x_clk)) {
+		err = PTR_ERR(cpufreq->pll_x_clk);
 		goto put_cpu;
 	}
 
-	pll_p_clk = clk_get_sys(NULL, "pll_p");
-	if (IS_ERR(pll_p_clk)) {
-		err = PTR_ERR(pll_p_clk);
+	cpufreq->pll_p_clk = clk_get_sys(NULL, "pll_p");
+	if (IS_ERR(cpufreq->pll_p_clk)) {
+		err = PTR_ERR(cpufreq->pll_p_clk);
 		goto put_pll_x;
 	}
 
-	err = cpufreq_register_driver(&tegra_cpufreq_driver);
+	cpufreq->dev = &pdev->dev;
+	cpufreq->driver.get = cpufreq_generic_get;
+	cpufreq->driver.attr = cpufreq_generic_attr;
+	cpufreq->driver.init = tegra_cpu_init;
+	cpufreq->driver.exit = tegra_cpu_exit;
+	cpufreq->driver.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK;
+	cpufreq->driver.verify = cpufreq_generic_frequency_table_verify;
+	cpufreq->driver.suspend = cpufreq_generic_suspend;
+	cpufreq->driver.driver_data = cpufreq;
+	cpufreq->driver.target_index = tegra_target;
+	cpufreq->driver.get_intermediate = tegra_get_intermediate;
+	cpufreq->driver.target_intermediate = tegra_target_intermediate;
+	snprintf(cpufreq->driver.name, CPUFREQ_NAME_LEN, "tegra");
+
+	err = cpufreq_register_driver(&cpufreq->driver);
 	if (err)
 		goto put_pll_p;
 
+	platform_set_drvdata(pdev, cpufreq);
+
 	return 0;
 
 put_pll_p:
-	clk_put(pll_p_clk);
+	clk_put(cpufreq->pll_p_clk);
 put_pll_x:
-	clk_put(pll_x_clk);
+	clk_put(cpufreq->pll_x_clk);
 put_cpu:
-	clk_put(cpu_clk);
+	clk_put(cpufreq->cpu_clk);
 
 	return err;
 }
 
-static void __exit tegra_cpufreq_exit(void)
+static int tegra20_cpufreq_remove(struct platform_device *pdev)
 {
-	cpufreq_unregister_driver(&tegra_cpufreq_driver);
-	clk_put(pll_p_clk);
-	clk_put(pll_x_clk);
-	clk_put(cpu_clk);
+	struct tegra20_cpufreq *cpufreq = platform_get_drvdata(pdev);
+
+	cpufreq_unregister_driver(&cpufreq->driver);
+
+	clk_put(cpufreq->pll_p_clk);
+	clk_put(cpufreq->pll_x_clk);
+	clk_put(cpufreq->cpu_clk);
+
+	return 0;
 }
 
+static struct platform_driver tegra20_cpufreq_driver = {
+	.probe		= tegra20_cpufreq_probe,
+	.remove		= tegra20_cpufreq_remove,
+	.driver		= {
+		.name	= "tegra20-cpufreq",
+	},
+};
+module_platform_driver(tegra20_cpufreq_driver);
+
+MODULE_ALIAS("platform:tegra20-cpufreq");
 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
 MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
 MODULE_LICENSE("GPL");
-module_init(tegra_cpufreq_init);
-module_exit(tegra_cpufreq_exit);
-- 
2.17.0