Drivers for MMC hosts that accept phase corrections can take advantage
of the helper by embedding a mmc_clk_phase_map_t object in their
private data and invoking mmc_of_parse_clk_phase() to extract phase
parameters. It is the responsibility of the host driver to translate and
apply the extracted values to hardware as required.
Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx>
---
drivers/mmc/core/host.c | 43 ++++++++++++++++++++++++++++++++++++++++
include/linux/mmc/host.h | 17 ++++++++++++++++
2 files changed, 60 insertions(+)
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 96b2ca1f1b06..d03518f2e654 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -163,6 +163,49 @@ static void mmc_retune_timer(struct timer_list *t)
mmc_retune_needed(host);
}
+static void mmc_of_parse_timing_phase(struct device *dev, const char *prop,
+ struct mmc_clk_phase *phase)
+{
+ int degrees[2] = {0};
+ int rc;
+
+ rc = device_property_read_u32_array(dev, prop, degrees, 2);
+ phase->valid = !rc;
+ if (phase->valid) {
+ phase->in_deg = degrees[0];
+ phase->out_deg = degrees[1];
+ }
+}
+
+void
+mmc_of_parse_clk_phase(struct mmc_host *host, mmc_clk_phase_map_t map)
+{
+ struct device *dev = host->parent;
+
+ mmc_of_parse_timing_phase(dev, "clk-phase-legacy",
+ &map[MMC_TIMING_LEGACY]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-mmc-hs",
+ &map[MMC_TIMING_MMC_HS]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-sd-hs",
+ &map[MMC_TIMING_SD_HS]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-uhs-sdr12",
+ &map[MMC_TIMING_UHS_SDR12]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-uhs-sdr25",
+ &map[MMC_TIMING_UHS_SDR25]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-uhs-sdr50",
+ &map[MMC_TIMING_UHS_SDR50]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-uhs-sdr104",
+ &map[MMC_TIMING_UHS_SDR104]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-uhs-ddr50",
+ &map[MMC_TIMING_UHS_DDR50]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-mmc-ddr52",
+ &map[MMC_TIMING_MMC_DDR52]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-mmc-hs200",
+ &map[MMC_TIMING_MMC_HS200]);
+ mmc_of_parse_timing_phase(dev, "clk-phase-mmc-hs400",
+ &map[MMC_TIMING_MMC_HS400]);
+}
+
/**
* mmc_of_parse() - parse host's device-tree node
* @host: host whose node should be parsed.
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 01bba36545c5..bc4731c9738f 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -79,6 +79,22 @@ struct mmc_ios {
bool enhanced_strobe; /* hs400es selection */
};
+struct mmc_clk_phase {
+ bool valid;
+ u16 in_deg;
+ u16 out_deg;
+};
+
+/*
+ * Define a type to map between bus timings and phase correction values. To
+ * avoid bloat in struct mmc_host we leave it to the host driver to define the
+ * phase map object in its private data if it supports phase correction.
+ * However, mmc_of_parse_clk_phase() is provided by the mmc core and needs the
+ * provided array to be correctly sized, so typedef an appropriately sized
+ * array to minimise the chance that the wrong size object is passed.
+ */
+typedef struct mmc_clk_phase mmc_clk_phase_map_t[MMC_TIMING_MMC_HS400 + 1];
+
struct mmc_host;
struct mmc_host_ops {
@@ -490,6 +506,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *);
int mmc_add_host(struct mmc_host *);
void mmc_remove_host(struct mmc_host *);
void mmc_free_host(struct mmc_host *);
+void mmc_of_parse_clk_phase(struct mmc_host *host, mmc_clk_phase_map_t map);
int mmc_of_parse(struct mmc_host *host);
int mmc_of_parse_voltage(struct device_node *np, u32 *mask);
--
2.27.0
