[PATCH v10] mmc: Export host capabilities to debugfs.

[Harish Jenny K N]

This patch exports the host capabilities to debugfs

This idea of sharing host capabilities over debugfs
came up from Abbas Raza <Abbas_Raza@xxxxxxxxxx>
Earlier discussions:
https://lkml.org/lkml/2018/3/5/357
https://www.spinics.net/lists/linux-mmc/msg48219.html

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Harish Jenny K N <harish_kandiga@xxxxxxxxxx>
---

Changes in v10:
- minor review comment addressed. 
- Added "Reviewed-by" line

Changes in v9
- More code cleanup as suggested by Andy Shevchenko.

Changes in v8
- Changes to use for_each_set_bit as suggested by Andy Shevchenko.

Changes in v7
- Moved additional capabilities also to caps file as mentioned by Ulf Hansson
- compacting the code with macros

Changes in v6:
- Used DEFINE_SHOW_ATTRIBUTE

Changes in v5:
- Added parser logic in kernel by using debugfs_create_file  for caps and caps2 instead of debugfs_create_x32
- Changed Author

Changes in v4:
- Moved the creation of nodes to mmc_add_host_debugfs
- Exported caps2
- Renamed host_caps to caps

Changes in v3:
- Removed typecasting of &host->caps to (u32 *)

Changes in v2:
- Changed Author

 drivers/mmc/core/debugfs.c | 107 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)

diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
index c51e0c0..826d361 100644
--- a/drivers/mmc/core/debugfs.c
+++ b/drivers/mmc/core/debugfs.c
@@ -225,6 +225,110 @@ static int mmc_clock_opt_set(void *data, u64 val)
 DEFINE_SIMPLE_ATTRIBUTE(mmc_clock_fops, mmc_clock_opt_get, mmc_clock_opt_set,
 	"%llu\n");
 
+/*
+ * mmc_host_capabilities - MMC host capabilities
+ *
+ * This must be in sync with caps definitions in the mmc/host.h
+ */
+static const char * const mmc_host_capabilities[] = {
+	"4-bit transfers allowed",
+	"Supports MMC high-speed timing",
+	"Supports SD high-speed timing",
+	"Can signal pending SDIO IRQs",
+	"Talks only SPI protocols",
+	"Needs polling for card-detection",
+	"8 bit transfers allowed",
+	"Suspends (e)MMC/SD at idle",
+	"Nonremovable",
+	"Waits while card is busy",
+	"Allows erase/trim commands",
+	"Supports DDR mode at 3.3V",
+	"Supports DDR mode at 1.8V",
+	"Supports DDR mode at 1.2V",
+	"Can power off after boot",
+	"CMD14/CMD19 bus width ok",
+	"Supports UHS SDR12 mode",
+	"Supports UHS SDR25 mode",
+	"Supports UHS SDR50 mode",
+	"Supports UHS SDR104 mode",
+	"Supports UHS DDR50 mode",
+	"Unknown (bit 21)",
+	"Unknown (bit 22)",
+	"Supports Driver Type A",
+	"Supports Driver Type C",
+	"Supports Driver Type D",
+	"Unknown (bit 26)",
+	"RW reqs can be completed within mmc_request_done()",
+	"Supports Enable card detect wake",
+	"Can send commands during data transfer",
+	"CMD23 supported",
+	"Supports Hardware reset"
+};
+
+/*
+ * mmc_host_capabilities2 - MMC host additional capabilities
+ *
+ * This must be in sync with caps2 definitions in the mmc/host.h
+ */
+static const char * const mmc_host_capabilities2[] = {
+	"No access to Boot partition",
+	"Unknown (bit 1)",
+	"Can do full power cycle",
+	"Unknown (bit 3)",
+	"Unknown (bit 4)",
+	"Supports HS200 1.8V SDR",
+	"Supports HS200 1.2V SDR",
+	"Unknown (bit 7)",
+	"Unknown (bit 8)",
+	"Unknown (bit 9)",
+	"Card-detect signal active high",
+	"Write-protect signal active high",
+	"Unknown (bit 12)",
+	"Unknown (bit 13)",
+	"Can do complete power cycle of the card",
+	"Supports HS400 1.8V",
+	"Support HS400 1.2V",
+	"SDIO IRQ - Nothread",
+	"No physical write protect pin, assume always read-write",
+	"Do not send SDIO commands during initialization",
+	"Supports enhanced strobe",
+	"Do not send SD commands during initialization",
+	"Do not send (e)MMC commands during initialization",
+	"Has eMMC command queue engine",
+	"CQE can issue a direct command",
+	"Unknown (bit 25)",
+	"Unknown (bit 26)",
+	"Unknown (bit 27)",
+	"Unknown (bit 28)",
+	"Unknown (bit 29)",
+	"Unknown (bit 30)",
+	"Unknown (bit 31)"
+};
+
+static int mmc_caps_show(struct seq_file *s, void *unused)
+{
+	struct mmc_host *host = s->private;
+	unsigned long caps = host->caps;
+	unsigned long caps2 = host->caps2;
+	int bit;
+
+	seq_puts(s, "MMC Host capabilities are:\n");
+	seq_puts(s, "=============================================\n");
+
+	for_each_set_bit(bit, &caps, ARRAY_SIZE(mmc_host_capabilities))
+		seq_printf(s, "%s\n", mmc_host_capabilities[bit]);
+
+	seq_puts(s, "=============================================\n");
+	seq_puts(s, "MMC Host additional capabilities are:\n");
+	seq_puts(s, "=============================================\n");
+
+	for_each_set_bit(bit, &caps2, ARRAY_SIZE(mmc_host_capabilities2))
+		seq_printf(s, "%s\n", mmc_host_capabilities2[bit]);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(mmc_caps);
+
 void mmc_add_host_debugfs(struct mmc_host *host)
 {
 	struct dentry *root;
@@ -243,6 +347,9 @@ void mmc_add_host_debugfs(struct mmc_host *host)
 	if (!debugfs_create_file("ios", S_IRUSR, root, host, &mmc_ios_fops))
 		goto err_node;
 
+	if (!debugfs_create_file("caps", 0400, root, host, &mmc_caps_fops))
+		goto err_node;
+
 	if (!debugfs_create_file("clock", S_IRUSR | S_IWUSR, root, host,
 			&mmc_clock_fops))
 		goto err_node;
-- 
1.9.1