dmatest: restore ability to start test at module load and init

1/ move 'run' control to a module parameter so we can do:
   modprobe dmatest run=1.  With this moved the rest of the debugfs
   boilerplate can go.

2/ Fix parameter initialization.  Previously the test was being started
   without taking the parameters into account in the built-in case.

Also killed off the '__' version of some routines.  The new rule is just
hold the lock when calling a *threaded_test() routine.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

2 files changed, 116 insertions, 167 deletions

diff --git a/Documentation/dmatest.txt b/Documentation/dmatest.txt
index 45b8c95f1a21..e6e16a7f3706 100644
--- a/Documentation/dmatest.txt
+++ b/Documentation/dmatest.txt
@@ -15,17 +15,19 @@ be built as module or inside kernel. Let's consider those cases.
 
         Part 2 - When dmatest is built as a module...
 
-After mounting debugfs and loading the module, the /sys/kernel/debug/dmatest
-folder with a file named 'run' nodes will be created.  'run' controls run and
-stop phases of the test.
-
-Note that in this case test will not run on load automatically.
-
 Example of usage:
+        % modprobe dmatest channel=dma0chan0 timeout=2000 iterations=1 run=1
+
+...or:
+        % modprobe dmatest
         % echo dma0chan0 > /sys/module/dmatest/parameters/channel
         % echo 2000 > /sys/module/dmatest/parameters/timeout
         % echo 1 > /sys/module/dmatest/parameters/iterations
-        % echo 1 > /sys/kernel/debug/dmatest/run
+        % echo 1 > /sys/module/dmatest/parameters/run
+
+...or on the kernel command line:
+
+        dmatest.channel=dma0chan0 dmatest.timeout=2000 dmatest.iterations=1 dmatest.run=1
 
 Hint: available channel list could be extracted by running the following
 command:
@@ -42,7 +44,7 @@ The following command should return actual state of the test.
 
 To wait for test done the user may perform a busy loop that checks the state.
 
-        % while [ $(cat /sys/kernel/debug/dmatest/run) = "Y" ]
+        % while [ $(cat /sys/module/dmatest/parameters/run) = "Y" ]
         > do
         >       echo -n "."
         >       sleep 1
diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index 15199edcc366..c5048671daf7 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -21,10 +21,6 @@
 #include <linux/random.h>
 #include <linux/slab.h>
 #include <linux/wait.h>
-#include <linux/ctype.h>
-#include <linux/debugfs.h>
-#include <linux/uaccess.h>
-#include <linux/seq_file.h>
 
 static unsigned int test_buf_size = 16384;
 module_param(test_buf_size, uint, S_IRUGO | S_IWUSR);
@@ -70,45 +66,6 @@ module_param(timeout, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(timeout, "Transfer Timeout in msec (default: 3000), "
                  "Pass -1 for infinite timeout");
 
-/* Maximum amount of mismatched bytes in buffer to print */
-#define MAX_ERROR_COUNT         32
-
-/*
- * Initialization patterns. All bytes in the source buffer has bit 7
- * set, all bytes in the destination buffer has bit 7 cleared.
- *
- * Bit 6 is set for all bytes which are to be copied by the DMA
- * engine. Bit 5 is set for all bytes which are to be overwritten by
- * the DMA engine.
- *
- * The remaining bits are the inverse of a counter which increments by
- * one for each byte address.
- */
-#define PATTERN_SRC             0x80
-#define PATTERN_DST             0x00
-#define PATTERN_COPY            0x40
-#define PATTERN_OVERWRITE       0x20
-#define PATTERN_COUNT_MASK      0x1f
-
-struct dmatest_info;
-
-struct dmatest_thread {
-        struct list_head        node;
-        struct dmatest_info     *info;
-        struct task_struct      *task;
-        struct dma_chan         *chan;
-        u8                      **srcs;
-        u8                      **dsts;
-        enum dma_transaction_type type;
-        bool                    done;
-};
-
-struct dmatest_chan {
-        struct list_head        node;
-        struct dma_chan         *chan;
-        struct list_head        threads;
-};
-
 /**
  * struct dmatest_params - test parameters.
  * @buf_size:           size of the memcpy test buffer
@@ -138,7 +95,7 @@ struct dmatest_params {
  * @params:             test parameters
  * @lock:               access protection to the fields of this structure
  */
-struct dmatest_info {
+static struct dmatest_info {
         /* Test parameters */
         struct dmatest_params   params;
 
@@ -146,12 +103,58 @@ struct dmatest_info {
         struct list_head        channels;
         unsigned int            nr_channels;
         struct mutex            lock;
+        bool                    did_init;
+} test_info = {
+        .channels = LIST_HEAD_INIT(test_info.channels),
+        .lock = __MUTEX_INITIALIZER(test_info.lock),
+};
 
-        /* debugfs related stuff */
-        struct dentry           *root;
+static int dmatest_run_set(const char *val, const struct kernel_param *kp);
+static int dmatest_run_get(char *val, const struct kernel_param *kp);
+static struct kernel_param_ops run_ops = {
+        .set = dmatest_run_set,
+        .get = dmatest_run_get,
 };
+static bool dmatest_run;
+module_param_cb(run, &run_ops, &dmatest_run, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(run, "Run the test (default: false)");
 
-static struct dmatest_info test_info;
+/* Maximum amount of mismatched bytes in buffer to print */
+#define MAX_ERROR_COUNT         32
+
+/*
+ * Initialization patterns. All bytes in the source buffer has bit 7
+ * set, all bytes in the destination buffer has bit 7 cleared.
+ *
+ * Bit 6 is set for all bytes which are to be copied by the DMA
+ * engine. Bit 5 is set for all bytes which are to be overwritten by
+ * the DMA engine.
+ *
+ * The remaining bits are the inverse of a counter which increments by
+ * one for each byte address.
+ */
+#define PATTERN_SRC             0x80
+#define PATTERN_DST             0x00
+#define PATTERN_COPY            0x40
+#define PATTERN_OVERWRITE       0x20
+#define PATTERN_COUNT_MASK      0x1f
+
+struct dmatest_thread {
+        struct list_head        node;
+        struct dmatest_info     *info;
+        struct task_struct      *task;
+        struct dma_chan         *chan;
+        u8                      **srcs;
+        u8                      **dsts;
+        enum dma_transaction_type type;
+        bool                    done;
+};
+
+struct dmatest_chan {
+        struct list_head        node;
+        struct dma_chan         *chan;
+        struct list_head        threads;
+};
 
 static bool dmatest_match_channel(struct dmatest_params *params,
                 struct dma_chan *chan)
@@ -731,13 +734,24 @@ static bool filter(struct dma_chan *chan, void *param)
                 return true;
 }
 
-static int __run_threaded_test(struct dmatest_info *info)
+static int run_threaded_test(struct dmatest_info *info)
 {
         dma_cap_mask_t mask;
         struct dma_chan *chan;
         struct dmatest_params *params = &info->params;
         int err = 0;
 
+        /* Copy test parameters */
+        params->buf_size = test_buf_size;
+        strlcpy(params->channel, strim(test_channel), sizeof(params->channel));
+        strlcpy(params->device, strim(test_device), sizeof(params->device));
+        params->threads_per_chan = threads_per_chan;
+        params->max_channels = max_channels;
+        params->iterations = iterations;
+        params->xor_sources = xor_sources;
+        params->pq_sources = pq_sources;
+        params->timeout = timeout;
+
         dma_cap_zero(mask);
         dma_cap_set(DMA_MEMCPY, mask);
         for (;;) {
@@ -757,19 +771,8 @@ static int __run_threaded_test(struct dmatest_info *info)
         return err;
 }
 
-#ifndef MODULE
-static int run_threaded_test(struct dmatest_info *info)
-{
-        int ret;
-
-        mutex_lock(&info->lock);
-        ret = __run_threaded_test(info);
-        mutex_unlock(&info->lock);
-        return ret;
-}
-#endif
 
-static void __stop_threaded_test(struct dmatest_info *info)
+static void stop_threaded_test(struct dmatest_info *info)
 {
         struct dmatest_chan *dtc, *_dtc;
         struct dma_chan *chan;
@@ -785,39 +788,22 @@ static void __stop_threaded_test(struct dmatest_info *info)
         info->nr_channels = 0;
 }
 
-static void stop_threaded_test(struct dmatest_info *info)
-{
-        mutex_lock(&info->lock);
-        __stop_threaded_test(info);
-        mutex_unlock(&info->lock);
-}
-
-static int __restart_threaded_test(struct dmatest_info *info, bool run)
+static int restart_threaded_test(struct dmatest_info *info, bool run)
 {
-        struct dmatest_params *params = &info->params;
-
-        /* Stop any running test first */
-        __stop_threaded_test(info);
-
-        if (run == false)
+        /* we might be called early to set run=, defer running until all
+         * parameters have been evaluated
+         */
+        if (!info->did_init)
                 return 0;
 
-        /* Copy test parameters */
-        params->buf_size = test_buf_size;
-        strlcpy(params->channel, strim(test_channel), sizeof(params->channel));
-        strlcpy(params->device, strim(test_device), sizeof(params->device));
-        params->threads_per_chan = threads_per_chan;
-        params->max_channels = max_channels;
-        params->iterations = iterations;
-        params->xor_sources = xor_sources;
-        params->pq_sources = pq_sources;
-        params->timeout = timeout;
+        /* Stop any running test first */
+        stop_threaded_test(info);
 
         /* Run test with new parameters */
-        return __run_threaded_test(info);
+        return run_threaded_test(info);
 }
 
-static bool __is_threaded_test_run(struct dmatest_info *info)
+static bool is_threaded_test_run(struct dmatest_info *info)
 {
         struct dmatest_chan *dtc;
 
@@ -833,101 +819,61 @@ static bool __is_threaded_test_run(struct dmatest_info *info)
         return false;
 }
 
-static ssize_t dtf_read_run(struct file *file, char __user *user_buf,
-                size_t count, loff_t *ppos)
+static int dmatest_run_get(char *val, const struct kernel_param *kp)
 {
-        struct dmatest_info *info = file->private_data;
-        char buf[3];
+        struct dmatest_info *info = &test_info;
 
         mutex_lock(&info->lock);
-
-        if (__is_threaded_test_run(info)) {
-                buf[0] = 'Y';
+        if (is_threaded_test_run(info)) {
+                dmatest_run = true;
         } else {
-                __stop_threaded_test(info);
-                buf[0] = 'N';
+                stop_threaded_test(info);
+                dmatest_run = false;
         }
-
         mutex_unlock(&info->lock);
-        buf[1] = '\n';
-        buf[2] = 0x00;
-        return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+
+        return param_get_bool(val, kp);
 }
 
-static ssize_t dtf_write_run(struct file *file, const char __user *user_buf,
-                size_t count, loff_t *ppos)
+static int dmatest_run_set(const char *val, const struct kernel_param *kp)
 {
-        struct dmatest_info *info = file->private_data;
-        char buf[16];
-        bool bv;
-        int ret = 0;
-
-        if (copy_from_user(buf, user_buf, min(count, (sizeof(buf) - 1))))
-                return -EFAULT;
-
-        if (strtobool(buf, &bv) == 0) {
-                mutex_lock(&info->lock);
-
-                if (__is_threaded_test_run(info))
-                        ret = -EBUSY;
-                else
-                        ret = __restart_threaded_test(info, bv);
+        struct dmatest_info *info = &test_info;
+        int ret;
 
+        mutex_lock(&info->lock);
+        ret = param_set_bool(val, kp);
+        if (ret) {
                 mutex_unlock(&info->lock);
+                return ret;
         }
 
-        return ret ? ret : count;
-}
-
-static const struct file_operations dtf_run_fops = {
-        .read   = dtf_read_run,
-        .write  = dtf_write_run,
-        .open   = simple_open,
-        .llseek = default_llseek,
-};
-
-static int dmatest_register_dbgfs(struct dmatest_info *info)
-{
-        struct dentry *d;
-
-        d = debugfs_create_dir("dmatest", NULL);
-        if (IS_ERR(d))
-                return PTR_ERR(d);
-        if (!d)
-                goto err_root;
+        if (is_threaded_test_run(info))
+                ret = -EBUSY;
+        else if (dmatest_run)
+                ret = restart_threaded_test(info, dmatest_run);
 
-        info->root = d;
-
-        /* Run or stop threaded test */
-        debugfs_create_file("run", S_IWUSR | S_IRUGO, info->root, info,
-                            &dtf_run_fops);
-
-        return 0;
+        mutex_unlock(&info->lock);
 
-err_root:
-        pr_err("Failed to initialize debugfs\n");
-        return -ENOMEM;
+        return ret;
 }
 
 static int __init dmatest_init(void)
 {
         struct dmatest_info *info = &test_info;
-        int ret;
-
-        memset(info, 0, sizeof(*info));
+        int ret = 0;
 
-        mutex_init(&info->lock);
-        INIT_LIST_HEAD(&info->channels);
+        if (dmatest_run) {
+                mutex_lock(&info->lock);
+                ret = run_threaded_test(info);
+                mutex_unlock(&info->lock);
+        }
 
-        ret = dmatest_register_dbgfs(info);
-        if (ret)
-                return ret;
+        /* module parameters are stable, inittime tests are started,
+         * let userspace take over 'run' control
+         */
+        info->did_init = true;
 
-#ifdef MODULE
-        return 0;
-#else
-        return run_threaded_test(info);
-#endif
+        return ret;
 }
 /* when compiled-in wait for drivers to load first */
 late_initcall(dmatest_init);
@@ -936,8 +882,9 @@ static void __exit dmatest_exit(void)
 {
         struct dmatest_info *info = &test_info;
 
-        debugfs_remove_recursive(info->root);
+        mutex_lock(&info->lock);
         stop_threaded_test(info);
+        mutex_unlock(&info->lock);
 }
 module_exit(dmatest_exit);