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77 lines
2.6 KiB
Diff
77 lines
2.6 KiB
Diff
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From 50adadfaf324ed5cbb59ce2b85eda59de4e3801a Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.com>
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Date: Fri, 4 Dec 2020 15:20:36 +0000
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Subject: [PATCH] i2c: designware: Add SMBUS quick command support
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The SMBUS emulation code turns an SMBUS quick command into a zero-
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length read. This controller can't do zero length accesses, but it
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can do quick commands, so reverse the emulation. The alternative
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would be to properly implement the SMBUS support but that is a lot
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more work, and unnecessary just to get i2cdetect working.
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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---
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drivers/i2c/busses/i2c-designware-core.h | 2 ++
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drivers/i2c/busses/i2c-designware-master.c | 17 +++++++++++++++--
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2 files changed, 17 insertions(+), 2 deletions(-)
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--- a/drivers/i2c/busses/i2c-designware-core.h
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+++ b/drivers/i2c/busses/i2c-designware-core.h
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@@ -117,7 +117,9 @@
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#define DW_IC_ERR_TX_ABRT 0x1
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+#define DW_IC_TAR_SPECIAL BIT(11)
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#define DW_IC_TAR_10BITADDR_MASTER BIT(12)
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+#define DW_IC_TAR_SMBUS_QUICK_CMD BIT(16)
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#define DW_IC_COMP_PARAM_1_SPEED_MODE_HIGH (BIT(2) | BIT(3))
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#define DW_IC_COMP_PARAM_1_SPEED_MODE_MASK GENMASK(3, 2)
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--- a/drivers/i2c/busses/i2c-designware-master.c
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+++ b/drivers/i2c/busses/i2c-designware-master.c
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@@ -228,6 +228,10 @@ static void i2c_dw_xfer_init(struct dw_i
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ic_tar = DW_IC_TAR_10BITADDR_MASTER;
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}
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+ /* Convert a zero-length read into an SMBUS quick command */
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+ if (!msgs[dev->msg_write_idx].len)
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+ ic_tar = DW_IC_TAR_SPECIAL | DW_IC_TAR_SMBUS_QUICK_CMD;
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+
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regmap_update_bits(dev->map, DW_IC_CON, DW_IC_CON_10BITADDR_MASTER,
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ic_con);
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@@ -409,6 +413,14 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
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regmap_read(dev->map, DW_IC_RXFLR, &flr);
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rx_limit = dev->rx_fifo_depth - flr;
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+ /* Handle SMBUS quick commands */
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+ if (!buf_len) {
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+ if (msgs[dev->msg_write_idx].flags & I2C_M_RD)
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+ regmap_write(dev->map, DW_IC_DATA_CMD, 0x300);
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+ else
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+ regmap_write(dev->map, DW_IC_DATA_CMD, 0x200);
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+ }
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+
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while (buf_len > 0 && tx_limit > 0 && rx_limit > 0) {
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u32 cmd = 0;
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@@ -673,7 +685,7 @@ static const struct i2c_algorithm i2c_dw
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};
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static const struct i2c_adapter_quirks i2c_dw_quirks = {
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- .flags = I2C_AQ_NO_ZERO_LEN,
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+ .flags = 0,
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};
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static u32 i2c_dw_read_clear_intrbits(struct dw_i2c_dev *dev)
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@@ -813,7 +825,8 @@ void i2c_dw_configure_master(struct dw_i
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{
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struct i2c_timings *t = &dev->timings;
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- dev->functionality = I2C_FUNC_10BIT_ADDR | DW_IC_DEFAULT_FUNCTIONALITY;
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+ dev->functionality = I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_QUICK |
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+ DW_IC_DEFAULT_FUNCTIONALITY;
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dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
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DW_IC_CON_RESTART_EN;
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